3.3 Template Processing Requirements

The template population requirements include:

Requirement P.1: Processability of input data

Expression templates must be able to be processed against a specified input data (set of slot values). 

Input data should explicitly specify when multiple (or empty) slot values should be instantiated as multiple (or zero) attributes, multiple (or zero) groups, or multiple (or zero) full expressions. 

Requirement P.2: Cardinality and value constraints validity after processing

Processing of expression templates should validate any cardinality or value constraint expressed in the template. 

Requirement P.3: Syntactical validity after processing

Processing of an expression templates should result in a syntactically valid SNOMED CT expression, and hence conform to the ABNF rules of that language. For expression templates, the language to validate against is the SNOMED CT Compositional Grammar.

Requirement P.4: Substrate validity after processing 

If the expression template is being used as the definition of a precoordinated concept, the resulting expression must conform with the rules for representing content in RF2. For example, nested attribute values would not be allowed.

Requirement P.5: Concept model validity after processing

In some circumstances, it may be required for the resulting expression to be valid according to the concept model rules.