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Reference schema documents are one of the principal NIEM artifacts. They provide the authoritative definitions of broadly reusable schema components (e.g., data elements, types) from a given namespace (e.g., Core (nc), Screening (scr)).
- Explicit Conformance Target specified in the Naming and Design Rules (NDR)
- Broadest and most fundamental definitions of namespace components
- Provides authoritative semantics for namespace components
- Serves as the basis for IEPDs and Extension Schema Documents
The rules for development of reference schema documents are more restrictive than all other NIEM components to enforce the documents’ features:
- Has a uniform document structure.
- Does not restrict other data definitions.
- Does not use XML Schema’s restriction mechanism
xs:restriction.- Made as regular and simple as possible.
Extension schema documents (EXTs), like reference schema documents (REFs), are a fundamental part of NIEM model design. They contain components that use, or are derived from, the components in REFs and express additional vocabulary above and beyond the vocabulary available from REFs.
- Use explicit Conformance Target specified in the Naming and Design Rules (NDR).
- Define package-specific data elements and models.
- Extend vocabulary above and beyond that avaliable to REFs.
- Augment an existing NIEM data type (through NIEM Type Augmentation).
- Employ NIEM adapter types for components from an external standard that does not conform to NIEM.
- Limit the behavior of existing NIEM data types through schema
xs:restriction.- Can serve as the core schematic definitions of an IEPD.
Because the application of extension schema documents does not diverge much from reference schema documents, they must satisfy the same documentation requirements of reference schema documents.
Subset schema documents are NIEM artifacts that allow specification of a subset of the schema components defined with a given namespace. They are used in place of larger or more verbose Reference Schema Documents (REFs).
- Use same conformance target as Reference Schema Documents.
- Provide a self-consistent subset of definitions from a namespace.
- Provide a smaller basis to define NIEM-conformant packages.
- Can serve as the basis for Extension Schema Documents.
Subset Schema Documents are identically Reference Schema Documents (REFs) that provide a limited set of components from a namespace. They satify all the same rules and requirements of REFs but are typically found only within the specification of a NIEM-conformant package (i.e. IEPD or IEP). Subset Schema Documents are almost always automatically generated by SSGT. In fact, NIEM recommends against creating Subset Schema Documents manually.
Code List Artifacts (Code Lists) provide a method to specify categorical descriptors for data used within exchanges and IEPs. Code Lists in NIEM use one of two formats: Comma-Separated Values (CSV), or Genericode.
- simple machine-readable formats (CSV or Genericode)
- ability to specify code list references at Schema-Time (static) or Run-Time (dynamic)
- XML catalog support for URIs to actual code list files
- rules for matching abbreviated values to corresponding codes specified within a code list file
- serves as the basis for IEPDs and Extension Schema Documents
Code Lists, while functionally identical to schema enumerations, do not replace the established convention or deprecate the use of schema enumeration.
A Schema Document Set (SET) is a conceptual NIEM artifact that normalizes the rules and restrictions as they apply to a collection of NIEM-conformant schema documents. This conceptual artifact composes exactly one Schema, which is the sum rules and definitions defined within the set capable of validating Schema Instance Documents.
- Explicit Conformance Target specified in the Naming and Design Rules (NDR)
- Conceptual artifact for collection of schemas
- Resolves to exactly one Schema
- Capable of validating Schema Instance Documents
Because Schema Document Sets are composed of NIEM-conformant schema documents (either
REForEXT), each member document must adhere to the rules disignated by their individual conformance targets. Furthermore, the document set must also adhere to the rules applicable to the conformance targetSET.
Information Exchange Package Documenations (IEPDs) are the core NIEM artifacts. They represent the context, content, semantics, and structure of a defined information exchange. An IEPD consists of a set of artifacts that together define and describe one or more implementable information exchanges.
- Explicit Conformance Target specified in the Model Package Description Specification (MPD-Spec)
- The definitive artifact defining information exchanges
- Provides authoritative semantics for Information Exchange Packages (IEPs)
- Provides example derived IEPs and documentation
The rules for constructing IEPDs are defined by the Model Package Description Specification (MPD-Spec). IEPDs are a kind of MPD composed from other NIEM artifacts including, but not limited to: Code Lists, Extension Schema Documents, and Subset Schema Documents. IEPDs provide a self-contained definition for derived information exchanges, thus they must be self documenting.
Information Exchange Package (IEPs) are derived from superceding Information Exchange Package Documentation (IEPD) and define the exchange of information as NIEM artifacts. They are the messages exchanged between the stakeholders in the information exchange.
- Explicit Conformance Target specified in the Model Package Description Specification (MPD-Spec)
- The definitive artifact of an information exchange
- Provide consitent form of data
- Self-documenting NIEM artifact
The rules for constructing IEPs are defined by the Model Package Description Specification (MPD-Spec). IEPs are a kind of MPD derived from a subperceding IEPD. IEPs, by the MPD-Spec, must be self-documenting.