Pirep converter from acmi to pirep

Hi. I would like to write a python script that converts ACMI files into a PIREP and supplements necessary data (e.g., ICAO codes…). Is there any documentation on how such a Pirep must be structured? I find a lot about the API/REST, but unfortunately no documentation for manual Pireps that players can upload after a flight (not interested in live data). To accomplish this task, I’m trying to understand the PIREP Format.

regards marc