I recant.

Pigsonthewing was correct in his initial review. NCI Thesaurus ID is better to be treated as a pure Code string to be used across multiple Value Sets that NCI maintains mappings for.

In other words, the NCI Thesaurus ID Code string can be queried across multiple NCI URLs (sub databases) not only the NCIt database.

And it looks like we already created a property to hold the CUI Concept Unique Identifier that NCImetathesaurus (NCIm) uses as the top level identifier in its grand terminology database which holds complete mappings.

So, in short, we are in excellent shape for cross references.