Vivek, Hi
This was very Fast...
Thanks for the answer. Alas, it shows a way to preserve the integrity of the label, but not how to guarantee it (again, think SQL triggers). If somebody just does a CREATE STUDENT , or large LOAD CSV, without knowing about the "musician" label - integrity is gone: I will have (multiple?) students that are, indeed, musicians - without the Label.
I will keep looking.
Thanks again,
Shalom Elkin