The Cygnus-class (or Cygnus-subtype), also known as the MK-VIIB class, was a sub-type of the Hermes-class scouts and were ordered for Starfleet appropriation on stardate 5099 (late-2260s). Unlike the standard Hermes-class vessels, the Cygnus-class was designed to be outfitted for regular duties as command and diplomatic couriers. (TOS reference: Star Fleet Technical Manual)