Understanding M365 URI Strings

Greetings!

I have a question regarding the RequestType field when observing M365 logs. For context, I do analysis on incoming telemetry, and I noticed there's no clear documentation on what these request types mean.

As a reference, I also found this previous ticket where this gentlemen asked the same thing:

https://learn.microsoft.com/en-us/answers/questions/5318094/what-does-the-requesttype-column-mean-in-m365-logs

I'm curious to know if you're able to share what these various strings mean, and if you would be able to provide a clear concise definition. The biggest one I'm curious about is cmsi:cmsi as my colleagues and I are unsure of what this is doing exactly.

I appreciate your time!