1) All components identified with symbol and/or value (ex. CR4 1N4148)
2) No duplication of symbols.
3) All power busses properly labeled.
4) Distinction of different grounds. (ex. digital, analog, chassis)
5) Table showing last used and unused symbols.
6) Notes describing what status circuit is in, what position switches are in.
7) Critical voltages and test points on critical lines or i/o pins.
8) Notes on substitution tolerances.
9) Phase indication on coils or transformers.
10) Continuity of buss lines spanning pages.
11) Possible dotted lines isolating different circuits.
12) Notes pertaining to equipment used to perform tests.
13) Possible simple waveforms at critical points.
14) Verify polarity on all capacitors or polar components.
15) Components with wattages over the norm. identified.
16) Notes identifying circuit board numbers, assembly numbers, version numbers or table of versions.
17) Copyright statements, sheet numbers, proprietary statements.
18) Listing of bypass capacitors not necessarily in the active circuits.
19) Company logos or names, signatures and/or dates of engineer/project director and schematic creator.
20) Tolerance limits on critical components.
These are all I have come up with off the top of my head after over 25 years
of drawing schematics. I will add to this list as I remember more. Additional
input will be appreciated. Contact me, Thanks!