Ophiucus VI was an early name for the planet which became Ophiucus III. As such, Ophiucus VI was repeatedly referred to in the final draft script of TOS: "Mudd's Women".
In the novelization of "Mudd's Passion" (as published in Star Trek Log 3), Harry Mudd referred to this planet as a "charming frontier world."
According to Star Trek: Star Charts, the Ophiucus System (or 36 Opiuchi System) was located in non-aligned space in the mid-22nd century. In 2378, the system was located in or near Federation space. The system was a quadrinary star system. Ophiucus A was a K-class star with a magnitude of +3, which was ten times brighter than Sol. Ophiucus B, Ophiucus C, and Ophiucus D were K-class stars. This system was the namesake for the Ophiucus Sector (Sector 008). (pp. 19, 44, "United Federation of Planets I") Ophiucus Sector (or Sector 008) was the eighth sector explored by Earth ships. (p. 19)