All fashions worn on the show had a model sheet number. While the first 5 episodes (The Beginning to The Battle of the Bands) started out fairly simply, with the character's name and a number to signify the fashion, by the Starbright series they had a more precise numerical system for designating the Marvel Production code, and they proceeded to back-log the older fashions in the new format -making some artistic changes along the way; most obviously Roxy's main outfit change. The top left corner had a small box with several numbers. "5205" was the number for the Jem series in general. Following that was the number that designated the episode; for example, Hot Time in Hawaii's production code is MP 5205-18. Since the numbering system occurred around the Starbright era, the system is slightly anachronistic as far as the first 13 episodes are concerned, but by the time of The Music Awards, the numbers sort themselves out and the production codes numbers are roughly in line with the airing order.
Following the production code and episode number came the abbreviation of the character's name (JR would be Jerrica, J is Jem, RX is Roxy and so on) a dash and the fashion number. The fashion number would get higher as the series continued, so J-1 would *always* mean Jem's original pink outfit, no matter which episode it was shown on. By the time we get to episode 43 (Middle of Nowhere), Jem is already up to her 80th unique fashion. Usually, elsewhere on the model sheet, would be the same numbers in a slightly revised order. The model sheet shown left shows the hand written fashion number in the middle of the page J (for Jem)-41 (for the 41st Jem fashion) -18 (the episode number). The J-41-18 number would then be used by the storyboard artists as shorthand, to explain to the animators which fashion they wanted Jem to be wearing in that particular scene.
The "videos" often had fashions in them that would be needed only for the narrative for that specific video and would more often than not never be seen or used again. They were also often created by the videos' directors, not the main fashion designers for the show. Many of the "video" model sheets are designated with a "SONG" # in their codes.
Of course with any project that has as many people working on it as Jem did, there are a few goofs such as the same fashion number being used twice, Jetta/Raya episodes having earlier production codes than the Talent Search episodes - but for the most part it's a fairly consistent system!
Of course, this is all just general terms - the system if far from being 100% foolproof! It should be noted that post "Glitter and Gold" (or MP 5205-26, if you've been paying attention! ;) model sheets have been very difficult to find so I really can't comment too authoritatively about them, yet.
