When typesetting letters is common practice to have a reference such as:
Where the last number is incremented for each successive letter. Normally, I hand-code the number. When having hundreds of letters one tends to now and then make mistakes and duplicate or miss references.
Can someone propose a method to automate this with TeX? Important is to only increment once for each run, i.e., you don't want the counter to increment if you re-run the file. Please note I am out of inspiration for a MWE.
My suggestion, is probably one needs two files. The first one to totalize and a local per jobname to keep the specific letter reference.