Existing Wording: If MustSupport is false (or does not appear), and that element appears in a quality measure or in the matching criteria of a CDS artifact (e.g., the left-hand side or antecedent), the entire quality measure or CDS artifact may be ignored.

Comment:

I'm not sure we should specify this. E.g., the QICore Observation doesn't have component as mustSupport. This would imply that a rule that asked for a WBC check within a CBC would invalidate the entire rule. Perhaps that is an issue on the mustSupport status of that attribute, but it seems to me that we want QICore to be useful even in cases where attributes other than those marked mustSupport here are used. Otherwise, we might as well constrain out all the non mustSupport attributes. I think we should say instead that support for those attributes not marked mustSupport cannot be guaranteed, and perhaps that uses of non-mustSupport attributes should be explicitly flagged (e.g., in the description of an artifact, or by referencing a further constrained profile on QICore).

Summary:

Revisit MustSupport requirements