Field commission

A field commission (or brevet) refers to either a Starfleet commissioned officer holding a higher rank temporarily, or, in some cases, personnel from outside Starfleet temporarily being granted a Starfleet rank for the purpose of a specific mission.

Under normal circumstances those who receive a field commission will wear the rank insignia to which they have been commissioned. In 2371 a system was in place to allow those who had received field commissions to wear a provisional rank insignia, until the commission could be confirmed by Starfleet Command.

A field commission is not to be confused with a battlefield promotion, in which the officer in question is promoted while deployed in combat. This type of promotion is a permanent one.

Chronology

 * 2366 - Commander William Riker granted a field commission to Captain.
 * 2371 - Tom Paris, (offically an observer onboard the USS Voyager (NCC-74656)) granted a field commission to Lieutenant (j.g).
 * 2371 - When stranded in the Delta Quadrent, several Maquis operatives were granted field commissions aboard Voyager. These included Chakotay (commissioned as Lieutenant Commander) and B'Elanna Torres (commissioned as Lieutenant (j.g). Upon Voyager's return to Federation space, in 2377, all of these provisional commissions were accepted by Starfleet Command. ,
 * 2375 - Colonel Kira Nerys of the Bajoran Militia granted a field to commission to commander.


 * N.B. It is unclear why Tom Paris wore standard Starfleet insignia in Voyager while the other officers wore the 'provisional lozenges'. The out-of-universe answer suggests that the producers simply wished to make it clear which crewmembers were former Maquis.