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Affiliated Specifications

There are numerous schemas in XML and Express, or other data definition languages that handle certain aspects of data exchange in the AECOO domain at various levels from being proprietary to being a full open standard. This policy, once adopted by buildingSMART, identifies different levels of compatibility with buildingSMART. It serves to guide collaboration with other organizations and development teams. The criteria are applicable to specifications defined as Express (.exp) or XML (.xsd) schemas.

 

“buildingSMART schemas”

IFC is the single and complete schema of the IFC model published as an Express and XML schema that had been published for each major IFC release since IFC2x. The depth is needed to manage the comprehensive building industry data sets and is typically used on instances of entire buildings or large parts thereof. A typical example is the use of ifcXML as an alternative format for a comprehensive model view definition such as the coordination view.

Simplified schemas serve specific exchange requirements and relate to a valid subset of the complete schema of the IFC model. They are published with a more simplified structure that can manage a subset of the above. The schemas are related to the structure of IFC and generated automatically, but the generation is optimized to achieve a fundamentally simpler structure. The simplification may include (a) a legal subset only, then any file created using the simplified schema is automatically valid the "full" IFC schema, or (b) a structurally optimized schema, where a transformation is required to validate against the "full" IFC schema.

As a single simplified schema is specific to a model view definition satisfying one or several exchange requirements those requirements need to be documented as an Integrated Delivery Manual (IDM) and published as an official bSI MVD. "Simplified schema" means a specified methodology that generates simple schemas that remain IFC compatible.

IFC and full ifcXML are buildingSMART International standards and proposed ISO standards. Simplified schemas are published as buildingSMART International specifications together with the bSI official IDM and MVD.

 

”Affiliated schemas”

Well-formed and valid schemas that could be used to exchange relevant BIM data between two and more parties. These schemas shall be based on a defined use case and documented as an IDM. In addition to the schema a transformation to the appropriate subset of the IFC or ifcXML schema, using XSLT or similar formal specification formats, have been published. This guarantees a compatibility with the open international standard for Building Information Models.

Such an interoperable schema is acknowledged by bSI as an “affiliated schema”.

 

”Candidate schemas”

Well-formed and valid schemas that could be used to exchange relevant BIM data between two and more parties that have not been supported with an IDM use case specification. They may lack any mapping to IFC. However a two year period is given to allow liaison with buildingSMART groups and to create documentation of the schema at least as an IDM and to provide a transformation to the buildingSMART IFC standard.

Such an interoperable schema will be referred to as a "candidate for affiliation”.

 

Naming

 

 

 

 

buildingSMART status

Requirement

buildingSMART schema

Affiliated schema

Candidate schema

Criteria

 

 

 

 

Of interest to buildingSMART

Domain is AECOO

Yes

Yes

Yes

 

Completeness

Complete and applicable to more than one exchange or use-case.

Yes

Yes

Yes

 

MVD

Having a formal checkable and syntactically correct schema specification as Express or XSD

Yes

Yes

Yes

 

Schema documentation

Having full publically available documentation

Yes

Yes

Yes

 

IDM documentation

Having exchange requirement and resulting model view documentation

Yes and must be accepted by bSI

Yes

No, but achievable within 2 years.

 

Openness and standardization

In open domain or copyrighted by standardization body, or not-for-profit organization

Yes

Yes

No, but achievable within 2 years.

 

Formal mapping to IFC

Interoperable with buildingSMART schemas

Yes

Yes

No, but correlation to IFC must be published

Schema structures based on IFC

Based on IFC vocabulary

Yes

Maybe

Maybe

Copyright and ownership

Copyright to be with buildingSMART international

Yes

No

No