Editing High Level Architecture (section)

==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. 
[[File:Sample HLA Identification Table.png|thumb|Sample HLA identification table]]
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

[[File:Sample HLA object class table.png|thumb|Sample HLA object class table]]
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. 
[[File:Sample HLA attribute table.png|thumb|Sample HLA attribute table]]

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.
[[File:Sample HLA interaction class table.png|thumb|Sample HLA interaction class table]]

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.

[[File:Sample HLA parameter table.png|thumb|Sample HLA parameter table]]

===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====
[[File:Sample HLA simple datatype table.png|thumb|Sample HLA simple datatype 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====
[[File:Sample HLA enumerated datatype table.png|thumb|Sample HLA enumerated datatype 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====
[[File:Sample HLA array datatype table.png|thumb|Sample HLA array datatype 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====
[[File:Sample HLA fixed record datatype table.png|thumb|Sample HLA fixed record datatype 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.