https://en.wikipedia.org/wiki/Society_of_Motion_Picture_and_...

Didn't realize they were so broad in scope. The only thing I had heard of was "SMPTE codes" used in audio recording to sync up multiple multi-track recording machines, so that e.g. you could record 30 tracks using two 16-track recorders (with one track on each machine used for the sync). I never bothered to look up what SMPTE meant.