Concept ids and entity ids should be able to be identical

[jheeffer]

WS team requested DDF validator (warning) rule ENTITY_VALUE_AS_ENTITY_NAME which says concept ids and entity ids cannot be the same. I.e. there is a uniqueness constraint on the union of entity ids and concept ids.

This is not according to the definition of DDF. Concept id's and entity id's are two seperate sets of id's. Concept id's are unique within the set of concepts. Entity id's are unique within one entity domain. So it's possible to have male in both geo domain and gender domain (and male as a concept id) while still being a valid dataset and not creating problems in implementation.

We have this now for all our Gapminder sets where we have geo as a concept id for geographic places and geo as an entity id for Georgia. This is completely valid and shouldn't cause warnings.

I'm curious to hear how this creates problems in implementation.