At least for AB 5K, I name all my variables IN_XXX, AIN_XXX, OUT_XXX and AOUT_XXX.
E.g. IN_[P&ID#]_[TYPE(e.g. LS,ZSC, ZSO, whatever)].
This makes for easy Excel replacement of variables between emulated program and real IO program. Also makes commissioning IO check much easier because you can focus on real IO by sorting on one of the four types.
This requires use of Aliases. Use Aliases. Tie your real IO to anything but an Alias and you put yourself into a pickle for AB simulator. Don't do that. Use Aliasing and IN, OUT, AIN, AOUT and you've pretty much covered 99% of IO you'll encounter. Network IO notwithstanding.