Definitely a familiar request! To consolidate the ideas around schema field constraints, I'm marking this as a duplicate of these related ideas:
- constraints-schema-type-that-can-be-applied-to-fields
- multiple-values-check-box-in-schema-when-you-change-naxoccurs-from-unbounded
Please review and vote for these other ideas. Otherwise feel free to edit or propose edits to this idea to make it distinct from especially the Constraints Schema Type idea.