Daen, I haven't seen that covnention. I worked one job where we were required to inset and maintain zone blocks and the damn things were more trouble than they were worth. The company I work for now has bingo's on the borders but it's mainly so that we can converse with the non-CADs, suppliers and people dependent on paper copy.
That being said, I haven't come across a bingo system that gives you numbers along both axes. The good thing about the alphanumeric system is that it's almost universal across zoning applications, so everyone knows how to interpret it.
I personally have not seen that practice. The sheet numbers are usually tacken care of in the
title block and can be driven by Solidworks properties.
Most of the companies (or at least in the last 15 or so years) use ASME Y14.1-2005
which lays out the grid like you described as well as what is required in the titleblock.
I hope this helps you.
Scott and John,
Both great feedback. Good info to hear that the current ANSI does not follow this.