Star Trek ranks and uniforms - what an emotive subject and what a complete minefield!
Star Trek suffers badly from an apparent lack of logic and continuity where Starfleet uniforms are concerned and, at the end of the day, this is mainly down to the fact that it's a TV show for goodness sake!! There are massive inconsistencies and no amount of geeky pedantry can get around that - you just have to go with a best approximation and live with it!
There are some broad areas where consistent details of Starfleet uniforms and rank insignia are known for each era of Star Trek productions but, despite this, most of Trek falls down badly because there are HUGE areas where costume design, construction and useage did not follow established continuity. There are plenty of occasions where the wardrobe staff simply get it "wrong" or new costume designers modify an older uniform design but don't stik to the established style.
The producers also like the idea that they can change costumes and costume detailing when they want to; it adds interest and updates the look and feel of the show for the audience (which is entirely reasonable!) but from within the Star Trek universe it appears to run counter to any sense of reason that might exist in an organization as big as Starfleet when it comes to introducing new items of clothing at apparently random moments!
I have not yet found any DEFINITIVE reference material, whether in print or on-line (including many "official" books!), that does not include mistakes, misunderstandings / misinterpretations or conjectural designs to fill in the "gaps" - some of which are acknowledged as conjectural but some passed off as "canon" because the authors like their own work. The flag-rank cuff stripes for the Original Series uniform are a classic example of this - there are some regularly copied versions on the web but they are not in any way "canon" although they are often copied from one site to another and used as if they were.
Over the years, I've drawn up quite a few versions of Trek insignia from the various eras of the TV shows and the movies - and, yes, I've designed conjectural insignia to cover the gaps where some insignia have just never been seen. I'm always very careful to follow the stylistic details that HAVE been established and to take my cues from that. I also make sure that my designs maintain an internal consistency within whichever set of insignia I'm working. All of this means my versions of the "missing" are often quite different to some that are widely accepted BUT my designs are no more right or wrong than anyone else's...!!
Maybe Miklós is right - probably better not to discuss Trek at all...!!