In some of our downstream guides (e.g. PCDE) , we define what SHALL/SHOULD/MAY mean.  However, we should inherit that from HRex, and HRex should actually refer to the language here: http://hl7.org/fhir/conformance-rules.html#conflang

Suggest adding this at the beginning of the Conformance Expectations page:

Da Vinci IGs, including this one, make use of conformance language such as SHALL, SHOULD and MAY to describe the behavior of systems.  The meaning of these words shall be interpreted as per the [FHIR core spec](http://hl7.org/fhir/conformance-rules.html#conflang).