(covers information from several alternate timelines)
A signature was one's own name written in one's handwriting for the purpose of indicating that one had read or approved of a document or report. It could also be provided as identifying evidence on one's records.
In 2258 of the alternate reality, Montgomery Scott refused to sign an order authorizing advanced long-range torpedoes to be loaded onto USS Enterprise without looking at the specifications first. When Captain James T. Kirk ordered him to sign, Scott resigned instead. (Star Trek Into Darkness)