Student officer
According to a file was created for , a student officer was a title which could be held by a cadet at Starfleet Academy during the alternate 2250s.

In the personnel file of , he was identified as a student officer when he attended the Academy from 2255 to 2258. 

It is far from certain that the file in question was used in the film as much of the text was blurred. A clear vision of the file can be seen at G-Creative's web page for Star Trek: Beyond. 
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