In our design discussions, we discussed whether to bind Observation.code to a starter set of PACIO's ADI IG codes or a single code and decided to go with a single code for simplicity and to align with CCDA. Treating other codes like  PACIO's ADI IG codes as code translation was the compromise. Regarding the comment If we agree that as a minimum the code will hold the category and then any more specific codings as well, then we should try to apply that principle everywhere. We strive to maintain consistency within US Core across the wide variety of Profile and there use cases.  To that end, the pattern in US Core Treatment Intervention Preference Profile is the same as other narrowly defined observation profiles such as: US Core Observation Occupation Profile US Core Observation Pregnancy Intent Profile US Core Observation Pregnancy Status Profile US Core Observation Sexual Orientation Profile and until recently US Core Smoking Status Observation Profile