It's not entirely clear how the dependency tracing section should be understood / used. Please clarify the notation used for paths as well as how the paths should be understood (i.e., what exactly do they point to?).

If I understand the intent of the section correctly, I wonder if it is missing some things. For example:

• StructureDefinition
  • I noticed it only looks at differentials (and not snapshots). Is this because as long as you go up the baseDefinition inheritance tree, differentials will eventually cover everything?
  • Wouldn't you need to support anything pointed to by differential.element[].type.code, differential.element[].type.profile[], and differential.element[].type.targetProfile[]?
  • What about extension[]..url, and differential.element[].extension[]..url and the corresponding modifierExtension URLs?
• ValueSet
  • Should it list compose.incude[].system and compose.exclude[].system or do we assume all system-related data will be handled by a terminology server?

(These suggestions might not make sense if I'm misunderstanding the intent of this section).