I'm poking the sleeping bear . . .
It sounds like people are comfortable with a 2 part recommendation here:
1) Submit recommendation to the CDM WG to make all CONCEPT_IDs NOT NULL columns.
2) update language in the WIKI under CONCEPT_ID
Foreign key into the Standardized Vocabularies (i.e. the standard_concept attribute for the corresponding term is true), which serves as the primary basis for all standardized analytics. For example, condition_concept_id = 31967 contains reference value for SNOMED concept of 'Nausea'. Set the value to 0 'No matching concept' when a mapping to a standard concept cannot be found.
Anyone have more feedback . . . .