Introduction
A discussion paper from the Content Managers Advisory Group, entitled Discussion Paper - Allowance of Extensions to Modify Core Content has been submitted to SNOMED International management to resolve issues surrounding the interpretation of what national extensions are allowed to modify in the International release of SNOMED CT.
Background
The primary concern expressed is the interpretation of Clause 4.1 of the SNOMED CT® AFFILIATE LICENSE AGREEMENT, which states:
“Subject to clause 2.1.4, the Licensee may not modify any part of the SNOMED CT Core distributed as part of the International Release or as part of a Member’s National Release.”
Clause 2.1.4 states:
“(The Licensor grants the Licensee, license to) modify the manner of formatting of the copy of the SNOMED CT Core distributed to the Licensee as part of the International Release or as part of a Member’s National Release”
According to the discussion paper, there are two primary issues associated with this clause:
This restriction on modifications has been interpreted generally in two ways.
The RF2 distribution must not be modified, beyond appending additional rows. Overwriting data in the distribution files - such that an extension violates the append only model. Additionally, the full history provided by the international release must provided, i.e. extensions may not omit anything;
Core components must not be modified.
Overriding the international content through either:the addition of new versions for core components within extensions; or
the addition of relationships to core concepts and changing their DL definition.
2.Restrictions covered by B have been shown to be impractical and prohibit proper quality terminology authoring.