48 C.F.R. § 1815.606-70
An unsolicited proposal for a new effort or a renewal, identified by an evaluating office as being within the scope of an open NRA, shall be evaluated as a response to that NRA (see 1835.016-71), provided that the evaluating office can either:
[63 FR 9954, Feb. 27, 1998, as amended at 64 FR 48561, Sept. 7, 1999]