[RSLogix Tag Name Confusion]

I am trying to learn the logic of a process at my new job. There are tag names that I can't make sense of because they end with _xva, _xvb, _xvu, _xvd, _xvo, _xvc, _zsm, _zsu, _zsc, _zso, _zsd and so on and so forth. I know they are associated with motion, but I need to make better sense of them. There are no descriptors. What do they mean and is there a resource available that I can reference?

[RSLogix 5000 IO Mapping]

All of this information has been a big help to me with my current project. However, I did not write the current logic and need to get an inventory of the available I/O points. Without physically going out and counting them, how can I get that information? Bp