[gtld-tech] IANA ID for "internal" registrar

I'm wondering what IANA ID "internal" registrars (such as those owning the "nic" 2nd-level domain, or any registrars used for monitoring) should be allocated? I understand that there was some documentation that recommended using 9999 for the "registry" registrar. But since more registrars are likely needed (such as the ICANN monitoring registrar), we probably need more than one ID. Any recommendations on that? Otherwise, we'll proceed with counting "up" from 9999.. or down... or negative IDs? ;) Alex