hi Wayne,
how are you? DC has a "new" system for rent registry that is separate from all the other official paperwork they want (CofO, Business License, etc). From my own experience, it looks like the rent registry is a semi-voluntary effort that you can fill out separately from the other paperwork. They will ask you basic characteristic of your unit, the lease term (length, fee, etc) and other particulars. Fortunately it is not related to any technical or building inspections! (I know, right?)
I hope this helps,
ile