Commodores appear to be something of an oddity in Star Trek and there doesn't seem to be a consistent view on what they are or whether they even exist in a given era. IMO, the first is worthy of discussion, however the second is an unfortunate Americanism brought about potentially due to changes in the role/protocol of the Commodore making it less prevalent in the TNG era.
1) UESF definately had Commodores, Forrest appears to be a "junior flag officer".
2) Federation Starfleet (23rd Century and early 24th) appeared to have two to three billets for Commodores (that may also be separate ranks): "task force commander" (Cdre Wesley), "senior line officer" (Cdre Decker) and "junior flag officer" (the rest). The first and third types also share a distinct badge (starburst) that lacks the division indicators of Decker's 'pretzel' and the more common 'delta'.
3) Federation Starfleet (late 24th Century) appears to have abandoned regular use of the rank as all officers above Captain appear to be treated as "members of the Admirality" and therefore accorded the courtesy title of "Admiral" regardless of their actual rank. [for example Gregory Quinn wears a uniform similar to a TOS-era Commodore but is refered to as Admiral]. However, textual references suggest that some from of the rank still exists.
4) Post-TNG TrekLit has mostly followed the series, however at least one reference suggests that the use of "Commodore" in the "task force commander" role is permissable, if optional. It should also be noted that Galaxy-class Captains are already commanding the equivalent of two or three 23rd Century starships already so they might be 'protocol equivalent' to a Commodore anyway.
1) UESF definately had Commodores, Forrest appears to be a "junior flag officer".
2) Federation Starfleet (23rd Century and early 24th) appeared to have two to three billets for Commodores (that may also be separate ranks): "task force commander" (Cdre Wesley), "senior line officer" (Cdre Decker) and "junior flag officer" (the rest). The first and third types also share a distinct badge (starburst) that lacks the division indicators of Decker's 'pretzel' and the more common 'delta'.
3) Federation Starfleet (late 24th Century) appears to have abandoned regular use of the rank as all officers above Captain appear to be treated as "members of the Admirality" and therefore accorded the courtesy title of "Admiral" regardless of their actual rank. [for example Gregory Quinn wears a uniform similar to a TOS-era Commodore but is refered to as Admiral]. However, textual references suggest that some from of the rank still exists.
4) Post-TNG TrekLit has mostly followed the series, however at least one reference suggests that the use of "Commodore" in the "task force commander" role is permissable, if optional. It should also be noted that Galaxy-class Captains are already commanding the equivalent of two or three 23rd Century starships already so they might be 'protocol equivalent' to a Commodore anyway.