De acordo com a Página da Memória Alfa neste uniforme em particular, aquela pequena caixa preta eles usam é:
a life support monitor belt buckle (non-canonically named the perscan device)
Fora do canon, aprendemos mais sobre o dispositivo Perscan
The perscan (or perscan device) was a medical device used by Starfleet in the 23rd century. It was a tiny scanner-transceiver which monitored the body's vital signs and transmitted the results to sickbay at all times, providing them with continuous updates on their physical status. In the uniforms introduced in the 2270s, the perscan was part of the belt ornament. (TOS novelization: Star Trek: The Motion Picture)
Isso se encaixa com a observação de McCoy no início do filme sobre a enfermaria mais parecida com um laboratório de informática do que com uma instalação médica.