Va. Code Ann. § 59.1-503.5
An agreement that is otherwise sufficiently definite to be a contract is not invalid because it leaves particulars of performance to be specified by one of the parties. If particulars of performance are to be specified by a party, the following rules apply:
(2) If a specification materially affects the other party's performance but is not seasonably made, the other party:
2000, cc. 101, 996.