47 C.F.R. § 64.2329 – Format.

(a) A carrier shall provide subscriber list information obtained in its capacity as a provider of telephone exchange service to a requesting directory publisher in the format the publisher specifies, if the carrier's internal systems can accommodate that format.
(b) If a carrier's internal systems do not permit the carrier to provide subscriber list information in the format the directory publisher specifies, the carrier shall:
1. (1) Within thirty days of receiving the publisher's request, inform the directory publisher that the requested format cannot be accommodated and tell the directory publisher which formats can be accommodated; and
2. (2) Provide the requested subscriber list information in the format the directory publisher chooses from among the available formats.