Displaying

A number of options exist for displaying SNOMED CT Expression Constraints, including:

• Displaying the expression constraint using SNOMED CT Expression Constraint Language in its originally authored and stored form;
• Converting the expression constraint to use either all symbols (as per the Brief Syntax), or all human-readable operators (as per alternate text introduced in the Long Syntax);
• Enhancing the expression constraint by adding in terms that may have been omitted, or replacing the existing terms with either local-dialect Preferred Terms or Fully Specified Names;
• Hiding the SNOMED CT identifiers for each concept and displaying only the Preferred Terms;
• Enhancing the display by using different font colors for each different part of the expression constraint (e.g. identifiers, terms, vertical bars, and operators), and by using whitespace in a way that improves the readability of the expression;
• Automatically transforming the expression constraint into a human-readable string using a predefined algorithm. For example, a simple algorithm may convert the symbols to text and remove the concept identifiers – e.g. "descendants of fracture of bone: finding site = descendants or self of arm". More sophisticated algorithms may use pattern matching and predefined templates to construct a more natural string;
• Representing the operators, operands and attribute values of the expression constraint by populating a structured form. This approach is primarily suited to expression constraints with a consistent template, where the form can be pre-designed.

Which of these options is most appropriate to use when displaying expression constraints, will depend on a number of factors, including the type of users that will be viewing the constraints, the scope of the required constraint functionality, and the capabilities of the system implementation.