The general SNOMED CT language requirements include:
Requirement G.1: Backward compatibility
The language should be backwardly compatible with any version of the language that has previously been adopted as an IHTSDO standard. Note that the only exception to this rule is where an error in the syntax has been identified and subsequently fixed.
Requirement G.2: Consistency
Each logical feature of the language should have a single, consistent meaning across all the languages in the SNOMED CT family of languages. Each logical feature should also have a consistent set of syntax representations.
Requirement G.3: Sufficient and necessary
Each language must be sufficiently expressive to meet the requirements of the use cases for which it was designed. However, functionality without a corresponding use case will not be included, as this increases the complexity of implementation unnecessarily.
Requirement G.4: Machine processability
In order to facilitate the easy adoption by technical audiences, instances of each language must be able to be parsed into a logical representation using a machine processable syntax specification. This requirement will be met by defining the language syntax in ABNF.
Requirement G.5: Human readability
Non-technical stakeholders require that the language is as human readable as possible, while still meeting the other requirements. This is essential for both the clinical validation of language instances, as well as for education and training.