I will try using the following notation to communicate RPN program's effect on the stack and LASTX register:
[d,c,b,a][e]->oper. desc.->[d',c',b',a'][e']
The first array with four elements represents the stack where d and d' refers to content of the T stack register and a and a' to content in the X stack register. The e and e' in the single element
array refers to the LASTX register's content. Ofcourse actual letters or words used may be choosen to so fit the input/output for particular program.
So for example to describe sqrt:
[d,c,b,v][e]->sqrt->[d,c,b,sqrt(v)][v]
and addition:
[d,c,b,a][e]->+->[d,d,c,b+a][a]
Ofcourse there are other (better?) ways using tables or some kind of bar diagram but think this may work and have the advantage of being easy and fast to type in text only documents.
Anyone of your long time rpn hackers having an opinion on this topic?