The general SNOMED CT language requirements include:
Requirement G.1: Backward compatibility
The language must be backwardly compatible with any version of the language that has previously been adopted as an SNOMED International standard. This means that any expression that is valid based on the previous SNOMED CT Compositional Grammar standard
1 should also be valid based on this updated version. Please note that this requirement does not preclude extensions to the language which do not affect its backward compatibility.
Requirement G.2: Consistency
Each logical feature of the language should have a single, consistent meaning across all SNOMED computable 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 defined for the use cases it was designed for. 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 expressions, as well as for the education and training required to author expressions.
Based on correct parsing using the ABNF specification