Not sure why you are asking me about units, you could try making the variable names "Aunits". with double quotes, works in Bricscad, else you can use a foreach loop but I would use car & cadr in the loop, (list (list "aunits" 2)("list 'auprec"4)(......))
Just a suggestion for labelling, the character "A" is (chr 65) (chr x) so you can start with a number and each time you run the section lisp it will add 1 to the x, this will do up to 26. You can save the value of X by using ldata so when dwg is opened again you still have next value and can display that in a prompt. So Enter will give next value. Yes there is code for AA AB etc.
Why not a dynamic block then can have a single stretch parameter based on the two pick points.