Omega Glory”, Theiss mistakenly got the idea that each starship would have a unique insignia, from the fact that some starship officers in an earlier episode "Charlie X" wore a different insignia (see Civilian starship duty). He therefore designed a rectangular insignia worn by the captain and the chief medical officer of the USS Exeter. Shortly before October 7, 2018, a December 18 1967 memo to Theiss from producer Bob Justman was discovered. Justman noticed the error while reviewing footage and consulted with Roddenberry, who clarified that this indeed was a mistake: all Starfleet starship personnel are to wear the delta insignia as seen on the Enterprise crew uniform. Footage was not reshot to correct the error, but Justman made it clear it was not to be repeated. Going forward, the delta symbol remained consistent for all starship personnel, as seen in “Court Martial” and “The Tholian Web”. This was not publicized, leading to the "unique starship insignia" theory taking hold among fans. Confusion returned to the franchise during production of the Star Trek: Enterprise episode “In a Mirror Darkly”, which shows what happened to the lost USS Defiant appearing in the original series episode “The Tholian Web”. The Enterprise costume designers designed an insignia for the Defiant, based on the incorrect assumption that universal use of the delta symbol was in honor of the NCC-1701 Enterprise completing its first five-year mission. In all other Star Trek series and movies, the delta insignia is universal regardless of duty posting. The delta symbol has a number of variants, based on the ship's department served in: Command: Including helm and navigation functions; the basic delta with an elongated star is worn on a gold tunic and the captain's special green tunic. Science: The star is replaced with a circle representing a planet with its equator outlined. This is worn on a blue tunic. Operations: This includes Engineering, Security, and Communications. The symbol is a six-sided spiral shape. This is worn on a red tunic. A large number of security officers sacrificially die in landing party duty, leading to the meme "redshirt" which is often parodied in other media. Medical: Doctors wear the science insignia, and nurses wear the Red Cross, on blue tunics. Doctors occasionally wear scrubs in sick bay. There were slight variations in the delta insignia among the two pilots and production. In the first pilot, all delta insignia were