What prefixes should be used on reference designators for components of various types? I think we can all agree that "R##" refers to a resistor, "C##" refers to a capacitor, and "L##" refers to an inductor. Beyond that, it appears to be a mishmash of conventions.
I've seen both "IC" and "U" used for chips. "Q", "T", and "M" have been used for transistors and MOSFETs. Ordinarily, "D##" is used for diodes, but LEDs and Zeners get special treatment on some boards.
What standards are available for reference, and who endorses them? JEDEC, ISO, IEEE, and other standardization bodies are welcome references (though I'd prefer an inexpensive standard), but I'm also curious to see what's used at various companies other than my own.
Edit: What I'd really like to see is a list in an answer here which complies with the standard (even if it's just a quote).