if it's revocable isn't all the info in the persons social security number and it would just be input directly onto the personal return

Enter I for individual, it is not a trust that requires a different code until the person passes and it becomes irrevocable.

Yes, but working on the partnership return.  The partner is a revocable trust.   

A revocable trust reports on a 1040 with an SSN, just like an individual, the program may be expecting an EIN for a trust of any flavor.