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High Level Architecture

The High Level Architecture (HLA) is a standard for distributed simulation, used when building a simulation for a larger purpose by combining (federating) several simulations. The standard was developed in the 1990s under the leadership of the US Department of Defense and was later transitioned to become an open international IEEE standard. It is a recommended standard within NATO through STANAG 4603. Today the HLA is used in a number of domains including defense and security and civilian applications.

The purpose of HLA is to enable interoperability and reuse. Key properties of HLA are:
 * The ability to connect simulations running on different computers, locally or widely distributed, independent of their operating system and implementation language, into one Federation.
 * Ability to specify and use information exchange data models, Federation Object Models (FOMs), for different application domains.
 * Services for exchanging information using a publish-subscribe mechanism, based on the FOM, and with additional filtering options.
 * Services for coordinating logical (simulation) time and time-stamped data exchange.
 * Management services for inspecting and adjusting the state of a Federation.

HLA forms the basis for developing standardized and extendable FOMs in different communities, for example in aerospace and defense.

The architecture specifies the following components.

 * A Run-time Infrastructure (RTI) that provides a standardized set of services through different programming languages. These services include information exchange, synchronization and federation management
 * Federates that are individual simulation systems using RTI services.
 * A Federation Object Model (FOM) that specifies the Object Classes and Interaction Classes used to exchange data. The FOM can describe information for any domain.

Together the above components form a Federation.

The HLA standard consists of three parts:

 * 1)  IEEE Std 1516-2010 Framework and Rules, which specifies ten architectural rules that the components or the entire federation shall adhere to.
 * 2)  IEEE Std 1516.1-2010 Federate Interface Specification, which specifies the services that shall be provided by the RTI. The services are provided as C++ and Java APIs as well as Web Services.
 * 3) IEEE Std 1516.2-2010 Object Model Template Specification, which specifies the format that HLA object models, such as the FOM, shall use.

History and versions
HLA was initiated in the early 1990s when Dr. Anita K. Jones, the Director of Defense Research and Engineering within the US Department of Defense, gave the Defense Modeling and Simulation Office (DMSO) the task of “assuring interoperability and reusability of defense models and simulations”. In 1995 DMSO formulated a vision for modeling and simulation and established a modeling and simulation masterplan, which included the High Level Architecture.

Two protocols for M&S interoperability already existed: Distributed Interactive Simulation (DIS), focusing on real-time platform level simulation with a fixed object model, and Aggregate Level Simulation Protocol (ALSP) focusing on simulation of aggregate with time management, ownership management and flexible object models, called confederation models. The purpose of HLA was to provide one unified standard that would meet the simulation interoperability requirements of all US DoD components.

The development of HLA was based on four prototypical federations: the Platform Prototype Federation, the Joint Training Protofederation, the Analysis Protofederation and the Engineering Prototype Federation. The HLA specification was prototyped and refined, until HLA 1.3 was finally released. To facilitate usage outside of the defense community, HLA was then transitioned into an IEEE standard, maintained by Simulation Interoperability Standards Organization (SISO). To facilitate the migration for DIS users, a Federation Object Model corresponding to the fixed object model of DIS was also developed as the Real-time Platform Reference FOM (RPR FOM).

The following HLA versions exist:

HLA 1.3
HLA 1.3 was published in March 1998 by DMSO. It consists of:
 * U.S. Department of Defense, Rules Version 1.3
 * U.S. Department of Defense, High Level Architecture Interface Specification Version 1.3
 * U.S. Department of Defense, High Level Architecture Object Model Template Version 1.3

The US DoD also published interpretations for HLA 1.3:
 * U.S. Department of Defense, Interpretations of the High Level Architecture Interface Specification Version 1.3, Release 3

HLA 1516-2000
HLA IEEE 1516-2000 was published in 2000 by IEEE. It consists of:
 * IEEE Std 1516–2000 – Standard for Modeling and Simulation High Level Architecture – Framework and Rules
 * IEEE Std 1516.1–2000 – Standard for Modeling and Simulation High Level Architecture – Federate Interface Specification
 * IEEE 1516.1–2000 Errata (2003-oct-16)
 * IEEE 1516.2-2000 – Standard for Modeling and Simulation High Level Architecture – Object Model Template (OMT) Specification

Major improvements in IEEE 1516-2000 included an XML-based FOM with detailed data type specifications, as well as an improved DDM design.

The IEEE 1516-2000 standard was also complemented by a recommended development process as well as a recommended VV&A process:
 * IEEE 1516.3-2003 – Recommended Practice for High Level Architecture Federation Development and Execution Process (FEDEP). This standard would later become IEEE Std 1730-2010 Distributed Simulation Engineering and Execution Process (DSEEP)
 * IEEE 1516.4-2007 – Recommended Practice for Verification, Validation, and Accreditation of a Federation an Overlay to the High Level Architecture Federation Development and Execution Process

It was soon found that the 1516-2000 standard had APIs that were slightly different for each RTI implementation. SISO produced a standard with alternate, dynamic link compatible (DLC) C++ and Java APIs:

 * SISO-STD-004.1-2004: Standard for Dynamic Link Compatible HLA API Standard for the HLA Interface Specification (IEEE 1516.1 Version)
 * SISO-STD-004-2004: Standard for Dynamic Link Compatible HLA API Standard for the HLA Interface Specification (v1.3)

The DLC APIs were later merged into the main standard.

HLA 1516-2010 (HLA Evolved)
The IEEE 1516-2010 standard was published in August 2010 by IEEE and is commonly known as HLA Evolved. It consists of:
 * IEEE 1516–2010 – Standard for Modeling and Simulation High Level Architecture – Framework and Rules
 * IEEE 1516.1–2010 – Standard for Modeling and Simulation High Level Architecture – Federate Interface Specification
 * IEEE 1516.2-2010 – Standard for Modeling and Simulation High Level Architecture – Object Model Template (OMT) Specification

Major improvements in IEEE 1516-2010 include Modular FOMs, incorporation of the DLC APIs in C++ and Java, a Web Services API and Fault Tolerance.

Machine-readable parts of this version of HLA, such as XML Schemas, C++, Java and WSDL APIs as well as FOM/SOM samples can be downloaded from the IEEE 1516 download area of the IEEE web site. The full standards texts are available at no cost to SISO members or can be purchased from the IEEE shop.

HLA 1516-20XX (HLA 4)
The development of a new version of HLA started in January 2016 by SISO and is currently ongoing.

Technical overview
The HLA standard consists of three parts:

 * Framework and Rules, which specifies ten architectural rules that federates or the entire federation shall adhere to.
 * Federate Interface Specification, which specifies the services that shall be provided by the RTI. The services are provided as C++ and Java APIs as well as Web Services.
 * Object Model Template Specification which specifies the format that HLA object models, such as the FOM, shall use.

Common HLA terminology

 * Run-time Infrastructure (RTI): Software that provides a standardized set of services, as specified in the HLA Federate Interface Specification. There are seven service groups.
 * Federate: A system, such as a simulation, a tool or an interface to live systems, that connects to the RTI. Examples of tools are data loggers and management tools. A federate uses the RTI services to exchange data and synchronize with other federates.
 * Federation: A set of federates that connect to the same RTI together with a common FOM.
 * Federation Execution: A session, where a set of federates execute together in a federation with a specific objective, using the same RTI and FOM.
 * Federation Object Model (FOM): A document that specifies object classes, interaction classes, data types and additional data that is used for the information exchange in a federation. A FOM is an XML file that follows the format of the HLA Object Model Template and the associated XML Schema. Different FOMs are used for exchanging data for different application domains. There are standardized FOMs, called reference FOMs, that are commonly used as a starting point for FOM development. A FOM can be developed and extended in a modular way using FOM modules.
 * Simulation Object Model (SOM): A document that specifies object classes, interaction classes, data types and additional data that a particular simulation publishes and/or subscribes to in a federation. A SOM is also an XML file that follows the format of the HLA Object Model Template and the associated XML Schema. SOMs can also be developed and extended in a modular way using SOM modules.
 * Object: Objects are used to represent data that is persistent over some period of time and that have attributes that can be updated. They are defined in the FOM/SOM using an Object Class.
 * Interaction: Interaction are used to represent instantaneous events with parameters. An interaction that has been sent cannot be updated (as opposed to object classes). They are defined in the FOM/SOM using an Interaction Class.
 * Datatypes: The representation and interpretation of attribute and parameter data is specified in the FOM/SOM using HLA Datatypes.
 * Publish: A federate that publishes an object class with a set of attributes can register and delete instances of that object class and update its attribute values. A federate that publishes an interaction class can send interactions of that interaction class, together with associated parameter values.
 * Subscribe: A federate that subscribes to an object class with a set of attributes will discover registrations and deletions of instances of that object class and receive updates of subscribed attributes. A federate that subscribes to an interaction class will receive interactions of that interaction class, together with associated parameter values.

Interface specification
The RTI services are defined in the HLA Interface Specification. They are grouped into seven service groups. In addition to these services, the Management Object Model (MOM) provides services that makes it possible to inspect and adjust the state of the federation programmatically.

Most RTIs consist of a Central RTI Component (CRC), which is an executable and Local RTI Components (LRCs), which are libraries that are used by the federates. Services are provided through a C++ or Java API and also using Web services. In the C++ and Java APIs, services are invoked using calls to an instance of the RTI Ambassador class. The RTI delivers information to a federate using callbacks, which are delivered using calls to an instance of the Federate Ambassador class. In the Web Services API, defined using WSDL, calls are made, and callbacks are fetched, by the federate using Web Services requests and responses.

The service group descriptions below focus on key services. Exceptions and advisories are not included.

Federation Management Services
The purpose of Federation Management services, described in chapter 4 of the HLA Interface Specification, is to manage Federation Executions as well as federation-wide operations such as Synchronization Points and Save/Restore.

One set of Federation Management services manages the connection to the RTI, the federation execution and the set of joined federates. Key services are:

 * Connect and Disconnect from the RTI
 * CreateFederationExecution and DestroyFederationExecution that are used to create and destroy a federation execution
 * JoinFederationExecution and ResignFederationExecution that are used by a federate to join and resign a federation execution.
 * ConnectionLost, that is used by the RTI to inform a federate that it has lost its connection to the federation execution due to a fault
 * ListFederationExecutions that is used to retrieve a list of available federation executions for an RTI

Another set of services relates to synchronization points. These are federation-wide events where all, or selected federates are required to complete an operation, such as initializing a scenario, before the execution can continue. Key services are:

 * RegisterFederationSynchronizationPoint that is used to register a synchronization point
 * AnnounceSynchronizationPoint that is used by the RTI to inform federates that a synchronization point has been registered
 * SynchronizationPointAchieved that is used by a federate to indicate that it has achieved a synchronization point
 * FederationSynchronized that is used by the RTI to Inform federates that the federation is synchronized, i.e. all federates have achieved the synchronization point.

Yet another set of service relates to saving and restoring a federation execution. A save operation requires both the RTI and each federate to perform a save of their internal state. A restore operation requires both the RTI and each federate to perform a restore of their internal state. Key services are:

Save:
 * RequestFederationSave that is used to initiate a save of a federation
 * InitiateFederateSave that is used by the RTI to notify federates to start saving its state
 * FederateSaveComplete that shall be called by a federate when it has completed saving its state.
 * FederationSaved that is used by the RTI to notify federates that the federation is saved

Restore:
 * RequestFederationRestore that is used to initiate a restore of a federation
 * InitiateFederateRestore that is used by the RTI to notify federates to start restoring its state
 * FederateRestoreComplete that shall be called by a federate when it has completed restoring its state.
 * FederationRestored that is used by the RTI to notify federates that the federation is restored

Declaration Management Services
The purpose of Declaration Management services, described in chapter 5 of the HLA Interface Specification, is to enable federates to declare what information they wish to publish (send) and subscribe to (receive) based on object and interaction classes in the FOM. The RTI uses this information to route updates and interactions to subscribing federates. For an object class, publishing and subscribing are performed for a specific set of attributes. For interaction classes, the entire interaction, including all parameters, is published and subscribed. Key services are:

 * PublishObjectClassAttributes that is used to publish a set of attributes for a given object class.
 * SubscribeObjectClassAttributes that is used to subscribe to a set of attributes for a given object class.
 * PublishInteractionClass that is used to publish an interaction class including all parameters
 * SubscribeInteractionClass that is used to subscribe to an interaction class including all parameters

Object Management Services
The purpose of Object Management services, described in chapter 6 of the HLA Interface Specification, is to enable federates to share information about object instances and to exchange interactions.

Object instance names can be reserved or be automatically generated. Federates can register object instances of specified object classes, that are then discovered by subscribing federates. Attributes of these object instances can be updated. These updates will be reflected to subscribing federates. Interactions can be sent. These interactions will be delivered to subscribing federates. Key services are:

Objects:
 * ReserveObjectInstanceName that is used to reserve a name to be used for an object instance
 * RegisterObjectInstance that is used to register an object instance of a particular object class, either with a reserved name or an automatically generated name.
 * DiscoverObjectInstance that is used by the RTI to notify federates subscribing to particular object class that a new object instance has been registered.
 * DeleteObjectInstance that is used to delete an object instance
 * RemoveObjectInstances that is used by the RTI to notify federates that an object instance has been removed

Attributes:
 * UpdateAttributeValues that is used to provide updated attribute values for an object instance
 * ReflectAttributeValues that is used by the RTI to notify federates subscribing to particular attributes of updated values.

Interactions:
 * SendInteraction that is used to send an interaction of a particular interaction class, including parameter values.
 * ReceiveInteraction that is used by the RTI to deliver an interaction, including parameter values, to federates subscribing to a particular interaction class

Ownership Management Services
The purpose of Ownership Management services, described in chapter 7 of the HLA Interface Specification, is to dynamically manage what federate that simulates what aspect of an object instance. In HLA, only one federate is allowed to update a given attribute of a given object instance. That federate is considered the owner of the attribute. A federate that registers a new object instance will automatically be the owner of all attributes it publishes. In some cases, attributes of an object instance may become unowned, i.e. not owned by any federate.

Ownership management provides services for transferring ownership of one or several attributes at runtime, which can include a federate Divesting the attribute and another federate Acquiring the attribute. There are two main patterns: “pull” that are initiated by the acquiring federate and “push” that are initiated by the divesting federate.

Key services for initiating “pull” ownership are:
 * AttributeOwnershipAcquisitionIfAvailable which is used by a federate that wishes to acquire ownership of unowned attributes.
 * AttributeOwnershipAcquisition which is used by a federate that wishes to request ownership of a potentially owned attribute

Key services for initiating “push” ownership are:
 * AttributeOwnershipDivestitureIfWanted which is used by a federate that wishes to divest attributes only if there is some other federate that is standing by to acquire ownership of these attributes.
 * NegotiatedAttributeOwnershipDivestiture, which is similar but may also cause the RTI to try to find a new owner.
 * UnconditionalAttributeOwnershipDivestiture, which is used by a federate that wishes to give up ownership, even if no new owner can be found.

All object instances have a predefined attribute called HLAPrivilegeToDeleteObject. Only the owner of this attribute for an object instance is allowed to delete the object instance. Ownership of this attribute can be transferred at runtime using the above operations.

Time Management Services
The information exchange in an HLA federation takes place in real-time with immediate (Receive Order, RO) delivery of messages, unless HLA Time Management has been enabled. The purpose of HLA Time Management, described in chapter 8 of the HLA Interface Specification, is to guarantee causality and a correct and consistent exchange of time stamped messages (updates and interactions) in Time Stamp Order (TSO), no matter if the federation executes in real-time, faster-than-real-time, slower-than-real-time or as-fast-as-possible.

Some important concepts in HLA Time Management are:

Logical time: A time axis in HLA, starting at zero. Logical time is used for Time Management timestamps and operations. The logical time axis can be mapped to the scenario time of the federation. An example of such a mapping is to let zero represent the scenario time 8:00 of the 1-Jan-1066 and let an increment by one represent one second of the scenario.

Lookahead: A time interval specifying the lowest time in the future for which a federate will produce messages. For a federate with a fixed time step, this is usually the length of the time step.

Granted: A federate is granted (allowed to advance) to a particular logical time by the RTI, when all time-stamped messages up to that time have been delivered. The federate can then safely start calculating messages with a timestamp in the future. This timestamp may not be earlier than the granted time plus the federates lookahead.

Advancing: When a federate has finished producing data for the granted time plus the lookahead, it may request to be advanced to a later time, which also means that it promises not to produce any more messages with a time stamp less than the requested time plus the lookahead. The federate is now in the advancing state.

Time Regulating: A federate that sends time stamped events is considered Time Regulating since the time advance by other federates may be regulated by this.

Time Constrained: A federate that receives time managed events is considered Time Constrained since the reception of time stamped messages, constrains its time advance.

The main principles of HLA Time Management are that:
 * Each time-regulating federate assigns a time stamp to messages (updates and interactions) when they are sent, indicating the scenario time at which the message is valid.
 * The RTI manages delivery of messages to time-constrained federates, with messages from time-regulating federates delivered at the appropriate time using a Time Stamp Order queue.
 * Time-constrained federates request permission from the RTI to advance their time.
 * The RTI grants a time advance to a time-constrained federates when it is sure that the federate cannot receive a message with a time stamp in its past.

Example of Lookahead, granted and advancing:
 * 1) A federate uses a fixed time step of 10 and has a Lookahead of 10.
 * 2) The federate is granted to logical time 50 by the RTI. The RTI thus guarantees that all messages with time step less or equal to 50 have been delivered to the federate.
 * 3) The federate now has all the necessary data to correctly calculate and send messages for the granted time plus Lookahead, i.e. 60.
 * 4) When the federate has sent all messages with timestamp 60, it requests to be advanced to time 60. It thereby promises not to send any messages with a timestamp less than 70.
 * 5) The RTI delivers all messages with timestamp less or equal to 60 to the federate. It then grants the federate to time 60.
 * 6) Etc.

If at least one federate in the federation performs pacing, i.e. correlates their time advance requests with a real time clock, the federation may run in real time or scaled real time. Without pacing, the federation will run as fast as possible (e.g., federations that do not require human interaction at runtime nor interfaces with systems that depend upon a real-time clock can run as fast as computing resources will allow).

Key services include:
 * EnableTimeConstrained and EnableTimeRegulating that enables theses modes for a federate
 * TimeAdvanceRequest whereby a federate requests to be advanced to a specified logical time
 * TimeAdvancedGrant whereby the RTI informs a federate that it is granted to a specified logical time.
 * EnableAsynchronousDelivery that enables delivery of Receive Order messages both when a federate is in the granted and advancing state.

For event driven simulation it is also possible for a federate to request to be advanced to the next event using the following service:

 * NextMessageRequest whereby a federate requests to be advanced to the timestamp of the next message due for delivery to the federate, or a specified logical time, whichever has a lower timestamp.

Another important concept is Greatest Available Logical Time (GALT). The greatest time that each federate can be granted to, depends on the time that other federates have been granted to as well as their lookahead. The GALT for a federate specifies how far a federate can be granted, without having to wait for other federates to be granted. This is particularly interesting for a federate that joins late into a time managed federation.

Key services for GALT are:
 * QueryGALT that returns the GALT for the calling federate.

More advanced services include:
 * FlushQueueRequest whereby a federate can request delivery of all queued, timestamped messages, no matter how far in the future their timestamp is.
 * Retract whereby a federate can request that an already sent message is retracted. This is useful in optimistic simulation.

Data Distribution Management Services (DDM)
The purpose of DDM, described in chapter 9 of the HLA Interface Specification, is to increase scalability of federations by performing additional filtering of subscribed data beyond class and attribute subscriptions. Filtering can be based on continuous values (like latitude and longitude) or discrete values (like car brand).

Key concepts of DDM are:

Dimension: a named interval (0..n) used for filtering, with values starting with 0 and ending with an upper bound n. Data in the simulation domain is mapped to one or more dimensions. For example, dimensions for geographical filtering could be LatitudeDimension and LongitudeDimension. A dimension for filtering based on car brand could be CarBrandDimension.

Normalization function: a function that maps input values to integer values to be used in a dimension. An example is that a normalization function for the LatitudeDimension could map a latitude value ranging from -90.0 to +90.0 to an integer in the range 0..179. A normalization function for the CarBrandDimension could map a set of car brands Kia, Ford, BMW and Peugeot to an integer in the range 0..3.

Range: an interval on a dimension, specified by a lower bound (inclusive) and an upper bound (exclusive).

Region: a set of ranges, each one relating to a particular dimension. In the above example, a region could consist of the range (3..5) for LatitudeDimension (55..65) for LongitudeDimension and (0..1) for the CarBrandDimension. At runtime Region Realizations (objects) are instantiated to represent regions. The ranges of a region can be modified over time.

Region overlap: two regions overlap if, for all dimensions that they have in common, their ranges overlap.

At runtime, a federate can provide Regions when subscribing to object class attributes and interactions. Regions are also used when sending attribute updates and interactions. When DDM is used, attribute updates and interactions will only be delivered if there is a region overlap.

Key services for Regions are:
 * CreateRegion that is used to create a region with a specified set of Dimensions.
 * DeleteRegion that is used to delete a region.
 * CommitRegionModifications that is used to change the ranges of a dimension for a Region.

Key services for exchanging attribute updates with DDM are:
 * RegisterObjectInstanceWithRegions that is used to register an object instance with regions associated with its attributes.
 * AssociateRegionsForUpdates that is used to associate regions with attributes of an object instance.
 * SubscribeObjectClassAttributesWithRegions that is used to subscribing to attributes of objects where the regions used for subscription overlaps with the regions of the attributes.

Key services for exchanging interactions with DDM are:
 * SubscribeInteractionClassWithRegions that is used to subscribe to interactions where the regions used for subscription overlaps with the regions of the interactions.
 * SendInteractionsWithRegions that is used to send interactions with associated regions.

Support services
The HLA Support Services, described in chapter 10 of the HLA Interface Specification, provide a number of supporting services. These include:
 * Getting Handles (references) to be used in the above service calls.
 * Setting various runtime switches, in particular for advisories (notifications).
 * Controlling the delivery of callbacks.

Management Object Model
The purpose of the Management Object Model, described in chapter 11 of the HLA Interface Specification, is to provide services for managing a federation. This is performed using the MOM object and interaction classes. MOM objects are defined in a special FOM module called the MIM, that is automatically loaded by the RTI. Key MOM features include:
 * List and inspect properties of federates.
 * Inspect properties of the federation.
 * Get the content of the current FOM and FOM modules.
 * Inspect the state of Time management.
 * Inspect and modify publications and subscriptions of federates.
 * Inspect certain performance figures.
 * Inspect which federate that calls which HLA services.
 * Inspect status of synchronization points.

Object model template (OMT)
The OMT is a template used for describing Federation Object Models (FOMs) and Simulation Object Models (SOMs). FOMs and SOMs can be represented in a tabular format or using XML. The latter format is used when a FOM is loaded into the RTI.

In earlier versions of HLA, FOMs were monolithic, but the current version of the standard supports modular FOMs, i.e. several modules, covering different aspects of the information exchange, can be provided to the RTI.

A number of predefined classes, datatypes, dimensions and transportation types are provided in the standard. These are provided in the HLAstandardMIM.xml FOM module. Predefined concepts are prefixed with HLA, for example HLAobjectRoot and HLAunicodeString.

There are three different XML Schemas for the OMT:
 * The OMT DIF XML Schema, that verifies that an OMT document follows the basic OMT format, but not that it is complete and has referential integrity.
 * The OMT FDD XML Schema, that verifies that an OMT document contains enough information to be useful by an RTI. Note that this schema is provided in the Interface Specification.
 * The OMT Conformance Schema that verifies that an OMT document is complete and has referential integrity.

Identification Table
The purpose of the identification table is to provide meta-data about the model, to facilitate reuse of the FOM/SOM or federates. The following fields are specified:

 * General: Name, Type (FOM/SOM), Version, Modification date, Security classification, Release restriction, Purpose, Application domain, Description, Use limitation and Use history
 * Keywords: Keyword values and Taxonomy used
 * Point of contacts (POC): Type (Primary author/Contributor/Proponent/Sponsor/Release Authority/Technical POC), POC name, POC organization, POC telephone, POC email
 * References: Type (Text document/Spreadsheet/Powerpoint file/Standalone FOM/Dependency FOM/Composed from FOM), Identification (document name or FOM name)
 * Other
 * Glyph (Icon)

Object Classes Structure Table
The purpose of the object class structure table is to specify the class hierarchy (subclass/superclass) of the object classes that are used to instantiate objects in an HLA federation. Object class attributes are inherited from superclasses to subclasses based on this hierarchy. The root of the object class tree is known as HLAobjectRoot. An example of a fully qualified name of an object class is HLAobjectRoot.Car.ElectricCar

The following fields are specified for an object class in the hierarchy:
 * Name
 * Publication (Publish/Subscribe/PublishSubscribe/Neither)

Attribute Table
The purpose of the attribute table is to specify the attributes that are available for a given object class. Since attributes are inherited, an object class will have the union of all attributes that are locally defined on the object class or specified on any direct or indirect superclass.

The following fields are specified for an attribute
 * Object class name, for which it is defined
 * Attribute name
 * Datatype, defined in the Datatypes Table (see below)
 * Update type (Static/Periodic/Conditional/NA)
 * Update condition
 * D/A (Divest/Acquire/NoTransfer/DivestAcquire): Whether the attribute can be divested and or acquired using the HLA Ownership Services
 * P/S (Publish/Subscribe/PublishSubscribe/Neither): Whether the attribute can be published and/or subscribed. In a SOM, this information relates to the Federate described, in a FOM it relates to the entire federation.
 * Available Dimensions
 * Transportation (Reliable/BestEffort/other transportations described in the Transportation table)
 * Order (Receive/TimeStamp): Delivery order for attribute updates.

Interaction Class Structure Table
The purpose of the interaction class structure table is to specify the class hierarchy (subclass/superclass) of the interaction classes that are used to exchange interactions in an HLA federation. Interaction class parameters are inherited from superclasses to subclasses based on this hierarchy. The root of the interaction class tree is known as HLAinteractionRoot. An example of a fully qualified name of an interaction class is HLAinteractionRoot.CarCommand.Start.

The following fields are specified for an interaction class in the hierarchy:
 * Name
 * Publication (Publish/Subscribe/PublishSubscribe/Neither)

Parameter Table
The purpose of the parameter table is to specify the parameters that are available for a given interaction class. Since parameters are inherited, an interaction class will have the union of all parameters that are locally defined on the interaction class or specified on any direct or indirect superclass.

Dimensions table
The purpose of the dimensions table is to specify the DDM dimensions, used for attributes and interaction classes.

Time representation table
The purpose of the time representation table is to specify the datatypes used by the Time Management services.

User-supplied tag table
A user-supplied tag can be supplied when calling certain HLA services. The purpose of the user-supplied tag table is to specify the datatypes of these tags.

Synchronization table
The purpose of the synchronization table is to specify the synchronisation points used in a federation.

Transportation type table
The purpose of the transportation type table is to specify the available transportation types. There are two predefined transportation types: HLAreliable and HLAbestEffort.

Update rate table
The purpose of the update rate table is to specify the available maximum update rates.

Switches table
The runtime behaviour of the RTI can be controlled using a number of predefined switches. The purpose of the switches table is to provide initial values for these switches. Some of the switches can also be updated at runtime.

Datatypes
The purpose of the datatype tables is to provide specifications of the datatypes used for attributes, parameters, dimensions, time representation, user supplied tag and synchronization points. There are six categories of datatypes, with a separate tabular format for each of them.

Basic Data Representation Table
The purpose of the basic data representation table is to provide binary representations for use in other tables. A number of predefined basic datatypes are provided in the HLA standard: HLAinteger16BE, HLAinteger32BE, HLAinteger64BE, HLAfloat32BE, HLAfloat64BE, HLAoctetPairBE, HLAinteger16LE, HLAinteger32LE, HLAinteger64LE, HLAfloat32LE, HLAfloat64LE, HLAoctetPairLE and HLAoctet. The set of basic datatypes is usually not extended with user defined basic datatypes.

Simple Datatypes Table
The purpose of the simple datatypes table is to describe simple scalar data items. A number of predefined simple datatypes are provided in the HLA standard: HLAASCIIchar, HLAunicodeChar, HLAbyte, HLAinteger64time and HLAfloat64time. It is common to include user defined simple datatypes in a FOM.

Enumerated Datatypes Table
The purpose of the enumerated datatypes table is to describe data elements that can take on a finite discrete set of values. One predefined enumerated datatype is provided in the standard: HLAboolean. It is common to include user defined enumerated datatypes in a FOM.

Array Datatypes Table
The purpose of the enumerated datatypes table is to describe arrays of data elements (simple, enumerated, arrays, fixed records or variant records). A number of predefined simple datatypes are provided in the HLA standard: HLAASCIIstring, HLAunicodeString, HLAopaqueData and HLAtoken. It is common to include user defined array datatypes in a FOM.

Fixed Record Datatypes Table
The purpose of the fixed record datatypes table is to describe records with a fixed set of data elements (simple, enumerated, arrays, fixed records or variant records).

Variant Record Datatypes Table
The purpose of the variant record datatypes table is to describe records that may contain different, predefined sets of data elements. The different sets are called Alternatives. Which alternative that applies for a given variant record is indicated by a data element called the Discriminant.

Notes table
The purpose of the notes table is to provide annotations and additional descriptions of items in other tables.

HLA rules
The HLA rules describe the responsibilities of federations and the federates that join.

 * 1) Federations shall have an HLA federation object model (FOM), documented in accordance with the HLA object model template (OMT).
 * 2) In a federation, all representation of objects in the FOM shall be in the federates, not in the run-time infrastructure (RTI).
 * 3) During a federation execution, all exchange of FOM data among federates shall occur via the RTI.
 * 4) During a federation execution, federates shall interact with the run-time infrastructure (RTI) in accordance with the HLA interface specification.
 * 5) During a federation execution, an attribute of an instance of an object shall be owned by only one federate at any given time.
 * 6) Federates shall have an HLA simulation object model (SOM), documented in accordance with the HLA object model template (OMT).
 * 7) Federates shall be able to update and/or reflect any attributes of objects in their SOM and send and/or receive SOM object interactions externally, as specified in their SOM.
 * 8) Federates shall be able to transfer and/or accept ownership of an attribute dynamically during a federation execution, as specified in their SOM.
 * 9) Federates shall be able to vary the conditions under which they provide updates of attributes of objects, as specified in their SOM.
 * 10) Federates shall be able to manage local time in a way that will allow them to coordinate data exchange with other members of a federation.

HLA Evolved
The IEEE 1516 standard has been revised under the SISO HLA-Evolved Product Development Group and was approved 25-Mar-2010 by the IEEE Standards Activities Board. The revised IEEE 1516–2010 standard includes current DoD standard interpretations and the EDLC API, an extended version of the SISO DLC API. Other major improvements include:

 * Extended XML support for FOM/SOM, such as Schemas and extensibility
 * Fault tolerance support services
 * Web Services (WSDL) support/API
 * Modular FOMs
 * Update rate reduction
 * Encoding helpers
 * Extended support for additional transportation (such as QoS, IPv6,...)
 * Standardized time representations

Federation Conformance
In order to ensure the proper interaction between simulations, a way of testing federate conformance is defined. This involves ensuring that every class and interaction listed in the SOM for a particular federate is used according to the usage described, "PublishSubscribe", "Publish", "Subscribe" or "None".

STANAG 4603
HLA (in both the current IEEE 1516 version and its ancestor "1.3" version) is the subject of the NATO standardization agreement (STANAG 4603) for modeling and simulation: Modeling And Simulation Architecture Standards For Technical Interoperability: High Level Architecture (HLA).

Base Object Model
The Base Object Model (BOM), SISO-STD-003-2006 is a related standard by SISO to provide better reuse and composability for HLA simulations. It provides a way to specify conceptual models and how to map them to an HLA FOM.

Alternatives
In regards to the Distributed Modeling and Simulation (DM&S) industry the most often used alternative to the HLA, for real-time simulation of military platforms, is Distributed Interactive Simulation (DIS), IEEE 1278.1-2012, a simulation protocol. Most HLA RTI vendors also feature DIS in their products. As for middleware applications that most closely match HLA features, such as the publish and subscribe feature (P&S) see Data Distribution Service (DDS) which shares many of the same characteristics but having an open on-the-wire protocol for system interoperability.

Criticism
HLA is a Message-oriented middleware that defines as a set of services, provided by a C++ or Java API. There is no standardized on-the-wire protocol. Participants in a federation must use RTI libraries from the same provider and usually also of the same version, which in some cases is perceived as a drawback. Most current tools also provide interconnectivity through sockets.

title: High Level Architecture


text:
Spilsby

Spilsby is a market town and civil parish in the East Lindsey district of Lincolnshire, England. The town is adjacent to the main A16, 33 mi east of Lincoln, 17 mi north-east of Boston and 13 mi north-west of Skegness. It lies at the southern edge of the Lincolnshire Wolds and north of the Fenlands.

The town has been a rural market town for more than 700 years. It has changed little in size since the beginning of the 19th century. The town centre includes a range of small supermarkets, banks, traditional newsagents, baker, butchers, jewellers and clothing stores, together with public houses, cafes and fast-food takeaways.

At the centre of town is an open square or traditional market place, from which the four main town streets radiate. Markets take place on a Monday. As Spilsby is located within a predominantly agricultural area, much of the market produce consists of locally grown vegetables and meat.

The population of the town was 2,336 in the 2001 census, increasing to 3,045 at the 2011 Census.

Early history
The area has been occupied by humans since prehistoric times. Evidence for this can be found at nearby West Keal, where an Iron Age hill fort and defensive terraced earthworks were built at the tip of the Wolds promontory, overlooking the present town.

The Spilsby area was visited and occupied by the Romans during the 1st century and held by them until the 4th century AD. During the 1960s, an archaeological dig and field walk at nearby Keal Cotes, in a large field south of the village (where the A16 meets Hagnaby Lane), discovered tessellated mosaic floor tiles and roof tiles. These indicated that a substantial Roman villa or high-status Romano-British farmhouse once stood on the site. The recorded finds from the site are stored at the Museum of Lincolnshire Life in Lincoln, Lincolnshire. In 1849 six Roman funeral urns were dug up in nearby Fulletby.

Spilsby was probably named before or no later than the 9th-century period of Danish rule, which had extended for centuries. It derives from the term Spila's-by, where by is old Old Norse for "place of dwelling". Hence, it meant "Spila's village", Spila (pronounced "Spiller") having been the local Viking warlord or chieftain, who acted as head of the immediate area. The town was recorded in the Domesday Book of 1086 as "Spilesbei". In 1082 it was not much more than a large farmstead and few surrounding crofts under the squireship of the Bishop of Durham.

In 1255 a charter was granted to a John de Beke (or John Beck) to hold a weekly market in Spilsby each Monday and a three-day annual fair in July. Four years later, in 1259, the same John de Beke was granted a further charter to hold a three-day Christmas fair from 5–8 December. The next recorded charter to hold a weekly Monday market in the town and an annual fair in July was granted in 1302 to the Lord of the Manor, Norman noble Robert de Willoughby. A copy of this charter is in the parish church.

At the east end of the town centre's marketplace stands a medieval buttercross monument. The architectural historian Nikolaus Pevsner suggests that the Spilsby Buttercross dates from as early as the 14th and certainly no later than the 16th century. The stepped bases of these monuments were used by early traders on market day to display their goods, usually milk, cheeses and butter.

Standing in the centre of the marketplace is the Old Town Hall. More recently it has been used as a store and petrol station. In the 18th century the town civic offices, a small courtroom, and the town gaol, were in the upstairs level supported by the arches. The ground level was an open covered space used as the local corn exchange and for stalls by market traders that were protected from the weather.

The Manor of Eresby
An oft-repeated historical myth is that the Manor of Eresby, including the lands and parish of Spilsby, was awarded to Walter de Beke, sometime after 1083, by William the Conqueror. This myth is one of several generated in the writings of William Dugdale. However, the Domesday Book of 1086 shows that the manor of Spilsby was held in 1086 by the Bishop of Durham (St Cuthbert's) as both Lord and tenant-in-chief. The only Domesday entry for Walter of Bec is as Lord of Singleborough, under Walter Giffard, the tenant-in-chief.

Other sources indicate that another Walter de Bec, who may or may not be related to the aforementioned Walter, married Agnes of Tattershall, daughter of Hugh, son of Pinco FitzEudo. She brought Spilsby, and the Manor of Eresby, with her, those lands being gifted to her by William I.

The manor was held by the Beke family until the male line died out, leaving Alice, the daughter of John Beke, 1st Baron Beke of Eresby, and the sole heiress of Walter, 2nd Baron Beke de Eresby, her brother who died in about 1310. The manor passed to Robert de Willoughby by way of his father William de Willoughby's marriage to Alice de Beke in about 1254. The Willoughby family originated in nearby Willoughby in the Marsh. In 1313, Robert was summoned to parliament as the first Baron Willoughby de Eresby, a family line that continues to the 28th Baroness Willoughby de Eresby.

The original manor house from the 14th century stood near the site of the later mansion. It was probably demolished when the new manor was built. During excavations in the mid-1960s, fragments of the earlier dwelling were discovered. Many examples of medieval and post-medieval pottery shards were recovered from the site of the Eresby Manor's moat by archeologist E. H. Rudkin in 1966.

The new Eresby manor house was built by Charles Brandon, 1st Duke of Suffolk, in 1535. He acquired the property after marrying his ward, the fifteen-year-old Catherine Willoughby, daughter and heiress of the William, 11th Baron Willoughby de Eresby.

In 1769, the Manor House was destroyed by fire during the stewardship of the 19th Baron, who was also Duke of Ancaster and Kesteven. It is believed that a carpenter accidentally started a fire with his candle while he was working in the roof space. A 1771 plan shows that the house was built in an 'H' shape. The plan also shows details of the grounds, which included an orangery, cherry orchard, bowling green, dovecote, and an ash grove, all near to the house. The Manor House had originally been moated, but by 1771 the moat had been adapted as an ornamental fishing lake.

The Church of England parish church of St James is built of the local Spilsby green sandstone. Parts of it date from the late 14th century, although it has been much added to over the centuries. The church has important funerary monuments. The greenstone is a soft and porous stone that absorbs water. The church was recased in Lancaster stone. It can seat a congregation of around 750. The parish churchyard was closed to further burials when it ran out of available space in 1884.

To mark his inheritance of the title in 1349, the 3rd Baron, Sir John de Willoughby, built a private chapel on his estate. Dedicated to the Holy Trinity, it was endowed with collegiate status, with a master and up to twelve priests. When the head of the family founded the King Edward VI Grammar School in 1550, the school initially had no school building. The twenty or so children were taught in the Eresby chapel building for the next sixty years.

The Willoughby family provided a school house in 1611, by converting an agricultural building on the edge of the estate. In 1839 the school house of 1611 was replaced by a new school building that was constructed on its current site, with funds provided by the 25th Baron, who was the first Earl of Ancaster.

The site of the Manor House was partially excavated in the mid 20th century by archaeologist and folklorist Ethel Rudkin.

Bolingbroke Castle
Bolingbroke Castle was built in the nearby parish of Bolingbroke after 1220 by Ranulph de Blondeville, Earl of Chester and Earl of Lincoln. Henry de Bolingbroke, later to become King Henry IV at the age of thirty-two, was born at Bolingbroke Castle in 1366.

The castle was much damaged during the English Civil War and, after the nearby Battle of Winceby in October 1643, only the lower sections of the outer walls remained. The last standing section of the castle, the gatehouse, collapsed in 1815.

Bolingbroke's original walls, also constructed of Spilsby greenstone, were in an irregular hexagon, with round towers on five of the corners. The gatehouse consists of two towers built about 3 yards apart. Leading to a portcullis further inside was a drawbridge that spanned the moat. The moat encircled an area about 87 yards in diameter. The six walls were 6½ feet wide and varied in length from 16 to 32 ft long. There was a small priest door in the rear wall just above the moat water line. The castle garrison was supported and supplied by an important market village outside the castle walls. It included several small farms, a friary and salmon lakes, two mills, and the chantry church of St. Peter & St. Paul.

Gunby Hall
According to the dated keystone on the west doorway, Gunby Hall was built in 1700 by Sir Henry Massingberd. The mansion still stands in several acres of landscaped and wooded parkland, including gardens containing a blue gazebo. Locally born Poet Laureate Alfred, Lord Tennyson described it as "an English home... all things in order stored and a haunt of peace". The original words, written in his own hand, are framed and preserved in the hall's library.

During the Second World War, the Air Ministry attempted to build an airfield at Gunby that would have covered the estate and necessitated demolishing the mansion. The then-owner, Field Marshal Sir Archibald Montgomery-Massingberd, personally appealed to King George VI. The Air Ministry relented, redrawing the plans that resulted in building RAF Spilsby 2 mi further south at Great Steeping. The runway eventually ended only a few yards short of the Gunby estate boundary hedge.

Gunby Hall was one of the first major British mansion houses and estates to be presented to the National Trust in 1944. It is open to the public on limited days of the week during the summer, while remaining a private family residence for the remainder of the year.

Hundleby
Hundleby was an ancient parish that fell within Spilsby. It has not changed greatly in size or layout for the past two hundred years. The village population in 1801 was 218, and in 1901 it reached a peak of 528, mostly agricultural farm workers and their families. By 1971 the population had fallen to 439. It has remained fairly stable ever since with only minor fluctuations.

Hundleby's Anglican St Mary's parish church was rebuilt between 1853 and 1855, and seated around two hundred parishioners. The parish had a long-standing right to send three children to the Raithby parish free school. Hundleby's elementary school was built around 1860 and was enlarged in 1884 to accommodate up to 120 children.

Grace Swan Memorial Cottage Hospital was built in Hundleby during the late 19th century as a 25-bed in-patient facility. It was split between charity and private fee-paying wards, with its own operating theatre, maternity unit and resident surgeon. Closed by the local health authority as part of a rationalisation programme during the 1990s, the building is now a local health centre.

Spilsby Poor Law Union group of parishes had a workhouse in Hundleby, built in 1838. The workhouse was recorded in 1870 as having 280 residents. The workhouse was later converted into Spilsby's Gables Hospital, which was demolished in the early 21st century for the construction of new housing.

Spilsby in the 19th century
In 1833 a new cemetery of approximately one acre was established on Boston Road. White's 1842 Directory described Spilsby as being "a small, but thriving and well-built market town, pleasantly seated on an eminence, which overlooks an extensive tract of marshes and fens. Eresby is a small hamlet just south of town."

In 1839 the King Edward VI Grammar School had moved from its original 17th-century school building to a new school built on its current site in Spilsby. The grammar school building was abandoned during the 1990s after the two Spilsby secondary schools had amalgamated as Spilsby High School.

In the mid-19th century, several chapels for nonconformist Methodism were built in the town, including Wesleyan Methodist, Primitive Methodist and Independent Methodists. When the Independents built a new chapel in 1866, they converted their original chapel to a Sunday school. The Wesleyans built a chapel opposite the Buttercross, in Market Place, during 1878.

A prison for the area was built in Spilsby between 1824 and 1826. It occupied a site where Spence Street and West End now stand. The prison covered just over 2 acre surrounded by a high brick wall and fronted by a courthouse. It was enlarged in 1869 to provide 85 single cells. The prison was demolished in 1876, except for the small front area. This contained the sessions house with a Greek Doric-pillared portico, police station and town lockup. The Sessions House of 1826, where court quarter sessions for the district of Lindsey were held until 1878, is now home to the Spilsby Theatre and Arts Centre.

The town's gasworks were constructed in 1853, opening in 1854 on Ashby Road, bringing street and house lighting to the town for the first time. In 1908 the North East Lincolnshire Water Company opened a pumping station in Hundleby, with a 75,000-gallon reservoir on Raithby Hill. It brought tap water to homes in Spilsby for the first time.

In 1892 Spilsby Pavilion opened, with a further room opened in 1896, each room accommodating 300 to 400 people. At the time, the Pavilion was advertised as providing accommodation for "dancing parties and smoking concerts". The Masonic Lodge and Hall opened on Halton Road in 1913.

The parish had 22 acre set aside as "poor land", owning many tenements and the Red Lion public house. Annual rental revenue from these properties, £76-5s-0d (£76.25) in 1842, was distributed half-yearly among any poor in the parish who did not receive any other financial aid from the town's poor rates. As a result of the 1834 Poor Law Amendment Act, the parish became part of the Spilsby Poor Law Union, which covered 33 local parishes.

Railway connections
A small local railway company built a branch line from Firsby junction to Spilsby, which opened on 1 May 1868. The branch was just over 4 mi long and connected Spilsby to the King's Cross, London to Cleethorpes main line. The only other railway station on the branch line was Halton Holegate Halt. The necessary parliamentary permission had been obtained by an Act in July 1865 which incorporated the Spilsby & Firsby Railway Company with an authorised capital of £20,000 and loans of £8,333 for the construction of the 4 mi, single-track branch.

Construction of the railway began in March 1867. The ceremonial cutting of the first turf was performed by the local rector, the Reverend Rawnsley, who was standing in for the railway company's chairman Lord Willoughby de Eresby the 25th Baron. The railway was expected to be opened quickly but disputes with the contractors arose over the quality of their work, and several lengths of track had to be replaced. The Great Northern Railway bought out the Spilsby & Firsby Railway Company for £20,000 through an Act of Parliament on 25 July 1890.

Passenger services were suspended in 1939. A goods service for grain, potatoes, livestock and other agricultural products continued for nearly 20 years. Goods including petrol, paraffin and coal continued to come into Spilsby via the rail link up to its final closure on 30 November 1958.

The main station building was demolished in 1965. The engine shed has been used by agricultural suppliers as a shop and store, with new sections added. The original trackbed within the town has been built on, with most of it covered by the Vale Industrial Estate. Outside the town, most of the old track route to Firsby can still be seen in aerial photographs, marked by the avenue of trees and bushes.

Military connections
The Seventh Spilsby Rifle Volunteer Corps, an early part-time army detachment, part of the Volunteer Force, was formed in the town during 1860. At its height, the corps contained about 100 members. In 1872, Captain J. W. Preston was the officer in charge, supported by Lt George Walker, Ensign Robert MacKinder and drill-master Sergeant Thomas Ward.

In 1889 the Rifle Volunteer Corps, renamed as F Company of the First Volunteer Battalion, was based in Spilsby. Its commandant was the now-promoted Major George Walker. He was aided by Lt G. B. Walker and Lt W. Hoff, Acting Surgeon Lieutenant Francis John Walker and the acting chaplain Rev. Pownoll Kendall.

In 1899 Spilsby's Territorial Force Drill Hall was completed in Halton Road, built of solid red brick. The site also contained housing and quarters for the resident professional army sergeant instructors.

In 1912, C Company of the 5th Battalion Lincolnshire Regiment (Territorial Force) was formed in the town. The company's commandant was Captain H. S. Scorer (killed in action at Hohenzollern Redoubt on 13 October 1915 during the First World War), Surgeon Colonel Francis John Walker was the chief medical officer, and the regular army drill instructor was Colour Sergeant Wallace Cowling.

Royal Air Force in Spilsby
During the Second World War, RAF Spilsby, a bomber airfield designed for Lancaster bombers, was built at Great Steeping. It opened for operations on 20 September 1943. Later used by the United States Air Force as a strategic bomber base until 1958, the airfield was finally demolished in the late 1970s. The runways and perimeter track were torn up, with most of the crushed aggregate being used in the construction of the new Humber Bridge.

RAF Spilsby is commemorated by an airfield memorial standing just outside Great Steeping and by plaques in All Saints' Church, Great Steeping. Cropmarks showing the airfield's runway layout are still visible in aerial photographs.

Spilsby Air Training Corps formed in 1950 initially as a detached flight of the established Skegness squadron, becoming the 2266 Spilsby Squadron ATC in 1952. Falling membership resulted in the squadron's disbandment in 2005.

RAF Spilsby was rebuilt in the 1950s as a standby base in case of war. It was designated as a standby base for escort fighters only and never used, and there is no record of any aircraft ever landing here. The new runway was weak because of drainage problems.

Governance
Spilsby parish was traditionally in the East division of the ancient Bolingbroke Wapentake in the East Lindsey district in the parts of Lindsey. The parish was also in the Bolingbroke Soke. Kelly's 1913 Directory of Lincolnshire places the parish in the South Lindsey division of the county.

Spilsby, governed locally by Spilsby Town Council, is under East Lindsey District Council based at Manby.

Spilsby falls under the Louth and Horncastle Westminster parliamentary constituency. The sitting MP is Victoria Atkins.

Geography
The town is situated upon slightly elevated ground at the southwestern rim of the Lincolnshire Wolds. Spilsby has an extensive south-east view of a tract of marsh and fen land, bounded by Boston Deeps and the North Sea. It is within 12 mi inland from Skegness.

The Wolds comprise a series of low hills and steep valleys, underlain by calcareous chalk, green limestone and sandstone rock, laid down in the Cretaceous period under a shallow warm sea. The characteristic open valleys of the Wolds were created during the last ice age through the action of glaciation and meltwater.

Geographically, the Lincolnshire Wolds are a continuation of the Yorkshire Wolds, which run up through the East Riding of Yorkshire. The Wolds as a whole were bisected by the erosion of the waters of the River Humber. The fenlands, which stretch down as far as Norfolk, are former wetlands, consisting both of peat bogs and tidal silt marshes. They were nearly all drained by the end of the 19th century, when Spilsby had its longest period of Victorian expansion.

The drainage was organised into river drainage, the passing of upland water through the region, and internal drainage of the land between the rivers. The internal drainage was designed to be organised by levels or districts, each of which includes the fen parts of one or several parishes. Spilsby falls within the Witham Fourth District: East, West and Wildmore Fens; and the Townland, from Boston to Wainfleet.

Previous population counts
Historical population sizes for the town include:
 * 1801 – 932
 * 1821 – 1,234
 * 1841 – 1,434
 * 1861 – 1,467
 * 1881 – 1,423
 * 1911 – 1,464
 * 1931 – 1,654

2001 census
The latest figures are drawn from the 2001 census:

Population in 2001: 2,336

 * 47.3% male and 52.7% female
 * 26.3% single and never married, 47.8% married, the remainder split between separated, divorced and widowed
 * 98.6% White with 1.4% spread between Asian, British Asian, Indian and Chinese

 * 81.4% Christian, with 11% indicating no religion, and the remainder split between other religions

 * 56.1% employed, 20.3% retired and 3% unemployed, remainder in full-time education

 * 60.1% of households were owner occupied, significantly below the national average
 * 2011 census
 * The latest figures are drawn from the 2011 census.
 * Population: 3045
 * Number of households: 1398
 * Average household size: 2.1
 * Residents in households: 2992
 * Residents in communal living: 53
 * Area: 500 hectares
 * Population density (people per hectare): 6.10
 * Population density (people per hectare): 6.10

Ethnicity and religion
Spilsby had a population of 3,677 at the 2021 Census, of the results of it. Spilsby's ethnic makeup was 98.1% White and 1.9% other ethnics. Of the religious makeup of the parish, the around 54.8% were Christian, followed by 44.2% irreligious and other religions being less than 1%.

Economy
The area is predominantly a rural agricultural economy, with increasing tourism to Spilsby and the surrounding market towns in the Wolds.

Landmarks
Spilsby and nearby landmarks include Gunby Hall, a National Trust property open on selected days during summer months, the Buttercross monument, a statue to Sir John Franklin, Spilsby Theatre and Arts Centre, Northcote Heavy Horse Centre and Bolingbroke Castle.

The Battle of Britain Memorial Flight at nearby RAF Coningsby contains a flying collection, with a Lancaster bomber plus five Spitfire and two Hurricane fighters, plus a DC47 Dakota transport and two Chipmunk trainers. Lincolnshire Aviation Heritage Centre is in East Kirkby, Spilsby on the site of RAF East Kirkby. The museum commemorates the RAF's presence in Lincolnshire during the Second World War, with airfields such as RAF Scampton being in the flat Lincolnshire countryside. The museum contains one of the world's three remaining Lancaster bombers still capable of flying, although it does not currently fly. Plans were announced in March 2008 to raise the funds necessary to get the Lancaster into the air again.

Snipe Dales Nature Reserve and Country Park is next to the historic Civil War battlefield at nearby Winceby.

Rural pre school

 * Bright Sparks Kindergarten – Fen Road, Spilsby
 * Nestlings Nursery – Rookery Farm, Little Steeping
 * Skendleby Play School – Gunby

Urban pre school

 * Spilsby and Skegness Portage – Eresby Avenue, Spilsby
 * Spilsby Playgroup – Woodlands Road, Spilsby
 * Totschool Playgroup – Halton Road, Spilsby

Rural primary school

 * Great Steeping Primary School- mixed sex; approx 115 pupils (67 boys and 48 girls)
 * Halton Holegate C of E Primary School - mixed sex; approx 56 pupils (24 boys and 32 girls)
 * Partney C of E Primary School - mixed sex; approx 83 pupils (46 boys and 37 girls)
 * Toynton All Saints' Primary School - mixed sex; approx 92 pupils (42 boys and 50 girls)

Urban primary school

 * Spilsby Primary School - mixed sex; approx 254 pupils (132 boys and 122 girls)

Secondary education
King Edward VI Academy, is a coeducational bi-lateral secondary school and specialist Humanities College for children between the ages of 11 and 18. The bilateral status is unusual, with less than five similar arrangements in the whole of England and Wales, permitting those who have passed the 11+ examination and those that fail the exam to study separately but under the same roof.

The school is an amalgamation of two separate institutions, the King Edward VI Grammar School opened in 1550 and the Sir John Franklin Secondary Modern School, which opened in 1954. These schools were originally combined in 1991 as Spilsby High School, initially retaining both sites and renaming twice. In September 2008 a sixth form college was established that provides education for over-16s, with provision for study towards a BTEC National Diploma Studies in Business Studies.

The original 1837 grammar school building was abandoned and stood empty for several years, but could not be demolished due to its Grade II listing status. In 2007 the front portion of the old school was adapted as a community facility providing meeting rooms and access to IT use. The rear of the school was demolished and has been developed for new residential housing.

Special schools

 * Eresby School - Eresby Avenue, Spilsby. A special school for children aged between 2 and 19
 * The Jane, Lady Franklin School - Spilsby. A mixed sex urban community special school for 11- to 16-year-olds. Currently 45 pupils on roll

Religious sites

 * St James' Church – Church of England – Church Street & Boston Road
 * Church of Our Lady & the English Martyrs – Catholic – Church Road opposite Spilsby Theatre
 * Spilsby Methodist Church – opposite the Buttercross
 * All Saints' Church – Christian Fellowship
 * Spilsby Christian Fellowship – Halton Road

Public services and facilities
Spilsby has a variety of cafés, bakeries, delis, florists, butchers and other stores selling clothing, furniture, etc. It has a unique ice cream shop selling home made ice cream.

Market day is Monday.

There is a large Sainsbury's store, a Co-op, a doctor's surgery, dentist and a post office. The local library is housed in the Co-op.

There are multiple churches.

The largest playground, along with a playing field and pavilion, can be found on Boston Road.

Spilsby public houses are The White Hart Inn, Market Square; The King's Head, Gunby; The Bell Inn, Halton Holegate; The Hundleby Inn, Hundleby; and The Red Lion and The Nelson Butt Inn on Market Street and the George Hotel on Boston Road.

Bus services connect to Lincoln, Boston, Skegness, Horncastle, Alford and Spalding with onward connections to more distant locations provided by Lincs Roadcar, Brylaine, Translinc, Hunt's Coaches and Stagecoach.

Set in the Lincolnshire Wolds, the town is an ideal place to visit on its own, or on the way to the seaside or accompanying a visit to nearby Snipe Dales. There are some fantastic walks on the nearby Wolds and surrounding Spilsby.

Media
Local news and television programmes are provided by BBC Yorkshire and Lincolnshire and ITV Yorkshire. Television signals are received from the Belmont TV transmitter.

Local radio stations are BBC Radio Lincolnshire, Greatest Hits Radio Lincolnshire and Lincs FM.

The town is served by these local newspapers, Skegness Standard and East Lindsey Target.

Sports and recreation
Spilsby has football, bowls and hockey clubs, and a sports pavilion and playing fields on Ancaster Avenue. The Spilsby Show takes place on the playing fields every July, with proceeds supporting local charities.

Spilsby Town F.C. is a football club that was formed in 1881. The first team currently play in the Boston Cropleys Suzuki Premier Division. The Reserve team play in the first division. The league is not officially a member of the English football league system, but clubs have in recent years moved up to the Lincolnshire Football League and then the Central Midlands League or United Counties League (the 12th level of the football league pyramid). Spilsby Town are 3-times winners of the Lincolnshire Senior Cup in 1881–82, 1882–83 and 1883–84. Between 1880 and 1885 Spilsby Town entered the FA Cup each year but were unable to progress beyond the first round. Spilsby Juniors Football Club Spilsby Juniors was formed during the summer of 1998 when the Mid-Lincolnshire youth football league accepted an application to enter a single Under-12 team in that year's Division C. The club expanded and now runs four teams from Under-9s to Under-14s.

Spilsby holds dance and yoga classes at the High School on Monday nights and tai chi at the Town Hall on Tuesday evenings.

Twin towns

 * , France
 * , Germany

Notable people

 * David Gordon Blackbourn (born 1949 in Spilsby) - historian, author, and professor
 * Sir John Franklin - Royal Navy captain and polar explorer, Lieutenant-Governor of Van Diemen's Land (modern-day Tasmania), was born in Spilsby in 1786, and died during an expedition to the Arctic in 1847. His statue in Spilsby's town square bears the inscription "Discoverer of the North West Passage" – he might more accurately be described as a Seeker of it.
 * Joel Pott - musician and songwriter, born in Spilsby
 * Stephen Sackur - BBC TV journalist, born in Spilsby

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Spilsby


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Talk:Leather pride flag

Caption under the flag graphic is incorrect...
The Leather Pride Flag represents the Leather subculture. While many in that community, BUT NOT ALL, also participate in BDSM and various forms fetish play, the Leather Pride Flag is not representational of those practices. While it's origins are VERY well established in the gay male community, individuals identifying in the myriad of other sexual orientations have embraced and been embraced by the Leather community.

Leathermischief (talk) 20:20, 3 June 2016 (UTC)

External links modified
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 * Added archive https://web.archive.org/web/20100803065539/http://www.leatherarchives.org/exhibits/deblase/timeline2.htm to http://www.leatherarchives.org/exhibits/deblase/timeline2.htm
 * Added archive https://web.archive.org/web/20080101043327/http://www.leatherarchives.org/exhibits/deblase/tony.htm to http://www.leatherarchives.org/exhibits/deblase/tony.htm

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External links modified
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I have just modified 2 external links on Leather Pride flag. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
 * Added archive https://web.archive.org/web/20080915142834/http://www.leatherarchives.org/exhibits/deblase/pride.htm to http://www.leatherarchives.org/exhibits/deblase/pride.htm
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Requested move 22 December 2021

 * The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: not moved, but "Pride" will be lowercase. (closed by non-admin page mover) Jerm (talk) 00:22, 30 December 2021 (UTC)

Leather Pride flag → Leather flag – In aiming to have a naming convention for all pride flags, as well as in the aim of WP:CONCISE, the "pride" should be removed from the name. See lesbian flag, transgender flag, etc. However, if "pride" is not removed, it should be uncapitalized. ~BappleBusiness[talk] 23:41, 22 December 2021 (UTC) The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.
 * Oppose Unlike the other flags removing 'Pride' would be less clear. Though, i do agree it shouldn't be capitalized—blindlynx 18:42, 23 December 2021 (UTC)
 * Oppose "Leather flag" is misleading and unlike the lesbian and transgender examples which describe people without losing much context, "leather" here describes a community/culture. Additionally, most references to the flag include the word "pride", within this article, and elsewhere regarding its creation and subsequent uses. HalJor (talk) 20:38, 23 December 2021 (UTC)
 * Oppose per above but "pride" should not be capitalized in the title, so Move to Leather pride flag. Rreagan007 (talk) 22:00, 27 December 2021 (UTC)

Undo the move
See the previous section, @DarknessGoth777. This article should not have been moved. HalJor (talk) 01:06, 17 March 2024 (UTC)

The purpose of the article rename was in the service of vandalistic historical revisionism
For some reason, User:DarknessGoth777 is fanatically determined to rewrite history, and get Wikipedia to pretend that the "old guard leather" community did not exist. I find that distinctly annoying for a number of reasons, such as that the gay male "leathermen" were rather well-organized at a time when many other aspects of gay and lesbian communities in the U.S. were rather disorganized, and when many other sexualities and identities included on Wikipedia LGBTQ symbols templates and articles were then extremely obscure at best... AnonMoos (talk) 18:10, 18 March 2024 (UTC)

title: Talk:Leather pride flag


text:
Concept inventory

A concept inventory is a criterion-referenced test designed to help determine whether a student has an accurate working knowledge of a specific set of concepts. Historically, concept inventories have been in the form of multiple-choice tests in order to aid interpretability and facilitate administration in large classes. Unlike a typical, teacher-authored multiple-choice test, questions and response choices on concept inventories are the subject of extensive research. The aims of the research include ascertaining (a) the range of what individuals think a particular question is asking and (b) the most common responses to the questions. Concept inventories are evaluated to ensure test reliability and validity. In its final form, each question includes one correct answer and several distractors.

Ideally, a score on a criterion-referenced test reflects the amount of content knowledge a student has mastered. Criterion-referenced tests differ from norm-referenced tests in that (in theory) the former is not used to compare an individual's score to the scores of the group. Ordinarily, the purpose of a criterion-referenced test is to ascertain whether a student mastered a predetermined amount of content knowledge; upon obtaining a test score that is at or above a cutoff score, the student can move on to study a body of content knowledge that follows next in a learning sequence. In general, item difficulty values ranging between 30% and 70% are best able to provide information about student understanding.

The distractors are incorrect or irrelevant answers that are usually (but not always) based on students' commonly held misconceptions. Test developers often research student misconceptions by examining students' responses to open-ended essay questions and conducting "think-aloud" interviews with students. The distractors chosen by students help researchers understand student thinking and give instructors insights into students' prior knowledge (and, sometimes, firmly held beliefs). This foundation in research underlies instrument construction and design, and plays a role in helping educators obtain clues about students' ideas, scientific misconceptions, and didaskalogenic ("teacher-induced" or "teaching-induced") confusions and conceptual lacunae that interfere with learning.

Concept inventories in use
Concept inventories are education-related diagnostic tests. In 1985 Halloun and Hestenes introduced a "multiple-choice mechanics diagnostic test" to examine students' concepts about motion. It evaluates student understanding of basic concepts in classical (macroscopic) mechanics. A little later, the Force Concept Inventory (FCI), another concept inventory, was developed. The FCI was designed to assess student understanding of the Newtonian concepts of force. Hestenes (1998) found that while "nearly 80% of the [students completing introductory college physics courses] could state Newton's Third Law at the beginning of the course, FCI data showed that less than 15% of them fully understood it at the end". These results have been replicated in a number of studies involving students at a range of institutions (see sources section below). That said, there remain questions as what exactly the FCI measures. Results using the FCI have led to greater recognition in the science education community of the importance of students' "interactive engagement" with the materials to be mastered.

Since the development of the FCI, other physics instruments have been developed. These include the Force and Motion Conceptual Evaluation concept and the Brief Electricity and Magnetism Assessment. For a discussion of how a number of concept inventories were developed see Beichner.

In addition to physics, concept inventories have been developed in statistics, chemistry, astronomy, basic biology,  natural selection,   genetics, engineering, geoscience. and computer science.

In many areas, foundational scientific concepts transcend disciplinary boundaries. An example of an inventory that assesses knowledge of such concepts is an instrument developed by Odom and Barrow (1995) to evaluate understanding of diffusion and osmosis. In addition, there are non-multiple choice conceptual instruments, such as the essay-based approach and the essay and oral exams concept to measure student understanding of Lewis structures in chemistry.

Caveats associated with concept inventory use
Some concept inventories are problematic. The concepts tested may not be fundamental or important in a particular discipline, the concepts involved may not be explicitly taught in a class or curriculum, or answering a question correctly may require only a superficial understanding of a topic. It is therefore possible to either over-estimate or under-estimate student content mastery. While concept inventories designed to identify trends in student thinking may not be useful in monitoring learning gains as a result of pedagogical interventions, disciplinary mastery may not be the variable measured by a particular instrument. Users should be careful to ensure that concept inventories are actually testing conceptual understanding, rather than test-taking ability, language skills, or other abilities that can influence test performance.

The use of multiple-choice exams as concept inventories is not without controversy. The very structure of multiple-choice type concept inventories raises questions involving the extent to which complex, and often nuanced situations and ideas must be simplified or clarified to produce unambiguous responses. For example, a multiple-choice exam designed to assess knowledge of key concepts in natural selection does not meet a number of standards of quality control. One problem with the exam is that the two members of each of several pairs of parallel items, with each pair designed to measure exactly one key concept in natural selection, sometimes have very different levels of difficulty. Another problem is that the multiple-choice exam overestimates knowledge of natural selection as reflected in student performance on a diagnostic essay exam and a diagnostic oral exam, two instruments with reasonably good construct validity. Although scoring concept inventories in the form of essay or oral exams is labor-intensive, costly, and difficult to implement with large numbers of students, such exams can offer a more realistic appraisal of the actual levels of students' conceptual mastery as well as their misconceptions. Recently, however, computer technology has been developed that can score essay responses on concept inventories in biology and other domains, promising to facilitate the scoring of concept inventories organized as (transcribed) oral exams as well as essays.

title: Concept inventory


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Talk:History of Azerbaijan/Soviet Azerbaijan

The Soviet Azerbaijan region corresponds to the Albania region in old Greek sources, and the part north of the Kura river correponds to the Shervan country. In ancient times it was the home of Scythians; later it became a part of the Roman empire. In early third century most of its area was conquered by the Sassanid; in late seventh century it was taken by the Arabs; in seventeenth and eighteenth centuries it was a part of Iran [Persia], and was then turned over to Russia according to the treaties of Golestan (1813) and Torkaman-Chay (1828). After the fall of the Tsar government, it was occupied by the Allied. The Ottoman forces occupied Baku in September, 1918 and named the whole region Azerbaijan, due to the similiarity of its Turkic speaking people with the dwellers of Iran's Azarbaijan. In April, 1920, a soviet regime was established in Baku. In December, 1936, Azerbaijan became one of the republics of the USSR.

''The above article is based on the 1966 Persian Encyclopedia and may be a copyright violation. Please don't use for anything but reference.''


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Stoddard-Dayton

Stoddard-Dayton was a high quality car manufactured by Dayton Motor Car Company in Dayton, Ohio, US, between 1905 and 1913. John W. Stoddard and his son Charles G. Stoddard were the principals in the company.

History
In 1904, John Stoddard decided to exit the agricultural implement business from which he had earned his fortune and instead to manufacture high quality automobiles for the emerging market in the United States. He sent his son Charles to Europe to tour continental automobile manufacturers. Charles returned convinced that electricity and steam were outmoded forms of propulsion. The earliest cars used Rutenber engines ("Let your steed be worthy of your chariot") and had 4605 cc engines. Six-cylinder engines appeared in 1907. The final range consisted of three four-cylinder models and a Knight sleeve valve six.

The company adopted a strategy of building the highest quality motor cars with powerful engines. Henry J. Edwards (b. ca 1872 England–) was the auto designer and Chief Engineer of the company. Low-end models were dressed in 15 to 18 coats of paint, each coat hand sanded and rubbed out. The limousine model had 27 or 28 coats of paint, similarly applied. After assembly, each car was driven on public roads for 150 mi to 400 mi, then the engine was disassembled, the cylinders re-honed, valves touched up, and then reassembled and road tested again.

Cars began to be delivered in late 1905, sold as 1906 models. Stoddard established a reputation as winning race cars in sprint races, hill climbs and dirt track races all over the Midwest. Because these cars were all stock models, Dayton Motor Car lost no time in letting the motoring public know. In 1909, a two-seater Stoddard-Dayton won the first race at Indianapolis Motor Speedway, averaging 57.3 mi/h. The first pace car ever was a Stoddard-Dayton driven by Carl G. Fisher to start the Indianapolis 500 in 1911.

In 1906 there were three models:
 * Runabout, $1,250, equipped with 15 hp "T"-head engine
 * Touring car, $2,250
 * Limousine, $3,200, equipped with 35 hp engine (and 28 coats of paint)

Frank Lloyd Wright's first car was a 1908 Stoddard-Dayton Model K roadster.

In 1909, Stoddard-Dayton formed the Courier Car Co in Dayton to produce a smaller, lighter, and lower-priced version of the Stoddard-Dayton, called the Courier.

By 1911, Stoddard-Dayton offered twenty models with four different engines—limousines, landaulets, coupes, touring, torpedoes, roadsters, trucks, taxicabs, delivery wagons. Examples include:
 * "Savoy," $1,350, equipped with 28 hp engine
 * "Stratford," equipped with 38 hp engine
 * "Saybrook," equipped with 48 hp engine
 * "Special," equipped with 58 hp engine
 * "Stoddard-Dayton-Knight limousine," $6,250, with six-cylinder 70 hp engine

In 1912, about 25,000 automobiles in twenty-six models were manufactured. In June 1912, Stoddard-Dayton became part of the United States Motor Company, which advertised the Stoddard-Dayton line with the simple statement: "None can go farther. None can go faster." They made an advance purchase of a large volume of engines from Atlas Engine Works (Indianapolis, Indiana) and made commitments for 30,000 chassis, factors that contributed to financial instability. In February 1912, Charles Stoddard resigned as Vice President of United States Motor Company, and Henry Edwards resigned as Chief Designer to form the Edwards Motor Car Company. Stoddard remained a Director of USMC and continued his financial holdings. However, United States Motor Company went into receivership in late 1912 and failed in bankruptcy in 1913. The Stoddard-Dayton went down with it.

The assets of the Dayton Motor Car Company were purchased by the reorganized Maxwell where parts were manufactured for assembly at New Castle, Indiana and later Detroit, Michigan. In 1913, Maxwell continued to offer the Stoddard-Dayton models 30, 38 and 48 (Savoy, Stratford and Saybrook), although these may have been leftover 1912 models. The 1913 model 48 offered a self-starter and electric lighting for an additional $200. When Maxwell later was itself reorganized, it became part of Chrysler Corporation and the Dayton division became Chrysler AirTemp.

Stoddard-Dayton was slow to react to the emergence of a mass market and maintained a high-quality strategy after automobiles ceased to be exclusively rich men's status symbols. They were building cars as good as possible while Ford and General Motors were building as cheap as possible. Stoddard-Dayton continued to expand model offerings at all price points, but never changed fundamental manufacturing methods. The classic example of this was the 11-part radiator cap on the limousine—body, two pins, gasket, gasket retainer, screws, and latch. It was permanently attached to the radiator so that it could not be lost or stolen and could be opened with a flip of the locking lever, even when the engine was hot. Meanwhile, in Detroit, a Ford punch press was punching out caps and then an operation applied threads. True, the threads sometimes stuck and it could not be removed when the radiator was hot—but the Model T was selling for $399.

title: Stoddard-Dayton


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Svein Rosseland

Svein Rosseland (March 31, 1894, in Kvam, Hardanger – January 19, 1985, in Bærum) was a Norwegian astrophysicist and a pioneer in the field of theoretical astrophysics.

Biography
Svein Rosseland was born in Kvam, in Hardanger, Norway. Rosseland grew up the youngest of nine siblings. He went to his final exams in Haugesund in 1917 and then went to the University of Oslo. After only three semesters at the university, he left in 1919 to work as an assistant professor with the meteorologist Vilhelm Bjerknes at the Bergen School of Meteorology. In 1920 he went to the Institute of Physics (now the Niels Bohr Institute) in Copenhagen, where he met Niels Bohr and other prominent physicists, and where he wrote two seminal papers. He spent 1924–1926 as a Rockefeller Fellow at the Mount Wilson Observatory in Pasadena, California.

In 1927, Rosseland earned a PhD. from the University of Oslo. As a professor at the University of Oslo from 1928 to 1964, he built up and headed academics at the Institute of Theoretical Astrophysics (Institutt for Teoretisk Astrofysikk). Rosseland was a key participant when the University of Oslo built the Institute of Theoretical Astrophysics in 1934, using funding from the Rockefeller Foundation. Between 1929-30 he was a guest professor at the Harvard College Observatory. In 1934 he founded the journal Astrophysics Norvegica, published by the Norwegian Academy of Science and Letters. In 1936 he published his textbook Theoretical Astrophysics, which contained numerous original contributions. Rosseland was instrumental in the effort behind the building of the Oslo Analyzer, finished in 1938 and for four years the world's most powerful differential analyzer.

With the German occupation of Norway in World War II, he fled the country and went to the United States, where he was appointed a professor at Princeton University. In 1943 he went to London to work with the development of radar by the British Air Defense Ministry and later at the Admiralty, where he worked on underwater explosions. He was also a consultant for the U.S. Time Corporation, a company that later evolved into the Norwegian-owned company Timex Group USA. In the war's final years, he worked on military research at Columbia University.

Rosseland returned to Norway in 1946. In the postwar period he was involved in the development of the Norwegian research policy and was among those involved in the creation of the Institute for Energy Technology which was established in 1948 and Norwegian Academy of Technological Sciences which was founded during 1955. He was also the driving force behind the creation of Harestua Solar Observatory located at Gunnarshaugen in Oppland, which was inaugurated in 1954.

Rosseland was Norwegian delegate to the CERN Council in the early days of the organization.

Legacy

In 1957 he was decorated Commander of the Royal Norwegian Order of St. Olav. The minor planet 1646 Rosseland and the lunar crater Rosseland are named after him, as is the Rosseland mean opacity. The Institute of Theoretical Astrophysics at the University of Oslo is housed in "Svein Rosseland's House". In honor of the 100th anniversary of his birth, the Svein Rosseland Centenary Symposium was held at the Norwegian Academy of Science and Letters in Oslo during June 1994. A bust of him was also erected at Steinsdalsfossen near his home in Norheimsund.

Selected works

 * On the Internal Constitution of the Stars, 1925
 * The Principle of Quantum Theory, 1930
 * On the Stability of Gaseous Stars, 1931
 * Astrophysik auf atomtheoretischer Grundlage, 1931
 * Theoretical Astrophysics, 1936
 * Jorda og universet. Matematisk geografi, 1940
 * The Pulsation Theory of Variable Stars, 1949

title: Svein Rosseland


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Abbey, Saskatchewan

Abbey (2021 population: ) is a village in the Canadian province of Saskatchewan within the Rural Municipality of Miry Creek No. 229 and Census Division No. 8. This village is in the south-western region of the province, north-west of the city of Swift Current. Abbey is serviced by Highway 32 near Highway 738.

History
In 1910, the first post office used by area residents was Longworth, located in the home of Cassie Baldwin. The townsite of Abbey was originally owned by a man named D.F. Kennedy. In 1913, the Canadian Pacific Railway (CPR) bought a quarter section of land from him to build a rail line. The CPR gave Mr. Kennedy the honour of naming the community, giving it the name Abbey - the name of the Kennedy farm in Ireland. Abbey incorporated as a village on September 2, 1913.

Abbey Fire Hall
Abbey has one municipal heritage property on the Canadian Register of Historic Places, the Abbey Fire Hall. Constructed in 1919 in response to a large fire that threatened the community in September 1918, the fire station was part of an upgrade to fire protection in Abbey. The station remained in service until a new fire station was constructed in 1975. The station is currently not in use, however the siren on the station tower is still used to signal emergencies in the community.

Parks and recreation
Abbey Golf Club is a golf course about 0.5 km south-east of Abbey. It was built in 1950 and is a par 35, 9-hole course with sand greens and a total length of 2,085 yards.

Demographics
In the 2021 Census of Population conducted by Statistics Canada, Abbey had a population of $100$ living in $59$ of its $85$ total private dwellings, a change of NaN% from its 2016 population of $129$. With a land area of 0.73 km2, it had a population density of in 2021.

In the 2016 Census of Population, the Village of Abbey recorded a population of 129 living in 65 of its 88 total private dwellings, a NaN% change from its 2011 population of 115. With a land area of 0.77 km2, it had a population density of in 2016.

Geography
Abbey is located south of the South Saskatchewan River and north of the Great Sand Hills

Climate
Abbey experiences a semi-arid climate (Köppen climate classification BSk) with long, cold, dry winters and short, warm summers. Precipitation is low, with an annual average of 316.2 mm, and is concentrated in the warmer months.

title: Abbey, Saskatchewan


text:
High School Proficiency Assessment

The High School Proficiency Assessment (HSPA, pronounced "hess-pah" (/ˈhɛspə/) or sometimes just "H-S-P-A") was a standardized test that was administered by the New Jersey Department of Education to all New Jersey public high school students in March of their junior year until 2014-2015 when it was replaced by the PARCC. Together with the New Jersey Assessment of Skills and Knowledge (NJ ASK), which was administered in grades 3–8, the HSPA was part of a battery of tests used to assess student performance in New Jersey's public schools.

Assessment
The HSPA was administered over a course of three days simultaneously in all public high schools throughout the state of New Jersey. The exam tests students' proficiency in a variety of academic subjects including mathematics and language arts literacy. Beginning on September 1, 2001, state law in New Jersey required that all students pass the HSPA for high school graduation.

Students who did not pass the exam on their first try were given two opportunities to retake it during their senior (and final) year. Additionally, for those who were still unable to pass the exam or felt that they were "not good test-takers," the state department of education gave students the option of participating in a "Special Review Assessment" process (SRA) to demonstrate their academic abilities.

History
The exam, first administered in 1989, was originally called the High School Proficiency Test (abbreviated as HSPT) and was taken during the freshman year. If the examination was failed, it could be taken each year until it was passed. In 1993, only students who were in eleventh grade (Grade 11) were allowed to take the exam, and thus in 2001 the name was changed to HSPT-11 to reflect that policy alteration.

Students with severe disabilities who were unable to participate in the standardized assessment tests were given an Alternate Proficiency Assessment (APA). An APA was a portfolio-based assessment method used to measure academic progress. The APA was given to a student in each content area where the student's disability was so severe that the student was not receiving instruction in the skill being measured and the student could not complete any of the types of questions on the assessment in a content area even with appropriate changes and accommodations.

title: High School Proficiency Assessment


text:
Talk:History of Azerbaijan/Albania (ancient)

Albania: ancient land, north of Caucausia, at the west side of Caspian Sea, starting from Aras and Kura rivers extending north, approximately corresponding to the northeast of current Soviet Azerbaijan and south of present Dagestan. Its people, who were warrior Scythians, fought with Mithridates VI, the king of Pontus, against Pompeius. See also: Arran.

''The above article is based on the 1966 Persian Encyclopedia and may be a copyright violation. Please don't use for anything but reference.''