This excerpt taken from the VRSN 10-K filed Jul 12, 2007.
Functional and Performance Specifications
These functional specifications for the Registry TLD consist of the following parts:
1. Verisign Registry Operator Registrar Protocol;
2. Supported initial and renewal registration periods;
3. Grace period policy;
4. Nameserver functional specifications;
5. Patch, update, and upgrade policy; and
6. Migration to Extensible Provisioning Protocol Plan.
7. Performance Specifications