This excerpt taken from the VRSN 10-K filed Jul 12, 2007.
3.1.2 Renew/Extend Grace Period
The Renew/Extend Grace Period is a specified number of calendar days following the renewal/extension of a domain name registration period through an RRP Command Renew. The current value of the Renew/Extend Grace Period is five calendar days. If a Delete, Extend, or Transfer occurs within that five calendar days, the following rules apply:
Delete. If a domain is deleted within the Renew/Extend Grace Period, the sponsoring Registrar at the time of the deletion receives a credit of the renew/extend fee. The domain immediately goes into the Redemption Grace Period. See Section 3.2 for a description of overlapping grace period exceptions.
Extend (RRP Command Renew). A domain can be extended within the Renew/Extend Grace Period for up to a total of ten years. The account of the sponsoring Registrar at the time of the additional extension will be charged for the additional number of years the registration is extended.
Transfer (other than ICANN-approved bulk transfer). If a domain is transferred within the Renew/Extend Grace Period, there is no credit. The expiration date of the domain registration is extended by one year and the years added as a result of the Extend remain on the domain name up to a total of 10 years.
Bulk Transfer (with ICANN approval). Bulk transfers with ICANN approval may be made during the Renew/Extend Grace Period according to the procedures in Part B of the ICANN Policy on Transfer of Registrations between Registrars. The expiration dates of transferred registrations are not affected. The losing Registrars account is charged for the Renew/Extend operation.