Those White PCB Letters?

Question

I'm familiar with the basic markings on the circuit board (the white letters near the component i.e. an "R###" near a resistor, "C###" capacitor, "IC###" for ICs, etc.) but don't know what CF,OL,SF, or CR stand for. I'd really appreciate any help either the actual meanings of these letters or some place I could find out. Thanks!

Extra info:

Components labeled "CR" look like diodes, but I always thought diodes were marked "D"?

Components marked "CF" look like ceramic oscillators and may well be, but I'd like to know for sure.

Components marked "OL" have three pins and look almost like some kinds of chunky peanut butter...they have large-ish (~.4cm diameter) protuberances on one side and are flat on the other side. Said component is about 2.3cm long, .9cm wide, and 1.3cm tall.

Components marked "SF" look like they could be just about anything =). They come in a yellow "box" about .2cm x .6cm x 1.1cm and have two pins.

Any help is appreciated!

Answer 1

I think that CR  means "Crystal Rectifier" or in other words solid state diode,  I'm afraid I don't know any of the others.

Answer 2

There's no real standardization on this. It varies by designer and manufacturer. The most influental thing is what OrCAD uses.  

I use R, L and C for the basic passive discretes, D for diodes of any kind, X for crystals, U for ICs, Q for transistors and T for transformers.  

Fuses are F, relays are K, switches are SW, connectors to the outside CN, internal connectors (headers, jumpers) are J.

Specialty stuff like filters are all over the place because designers tend to make their own parts.