I use page-line or pageline for all wires including inputs/outputs. The rackslotchan convention seems food until you have to page through pages and pages of a 60 pages to find it. With page line convention, you can go right to the exact place in the diagrams to find what you need.
104-23. Tells me page/drawing 104 line 23.
We are using something like that for wires, and depending if there is a push button, switch, relay, fuse, etc, we add a letter or two. eg PB10423 is a push button in page 104 line 23.