This was written by RadiantX on CSDb, and put on Codebase by me (FTC).
It is a description of how to create labels on the fly in the ca65 assembler by using macros. In this particular example, the labels are generated using a repeat counter in a loop. The macro that is used goes like this:
.macro makeident lname, count .ident(.concat(lname,.sprintf("%d", count))): .endmacro
Using a macro like this it's possible to create labels using a repeat counter.
.repeat $100, I makeident "foo", I lda $1000 + I sta $2000 + I .endrepeat
This produces the following code:
foo0: lda $1000 sta $2000 foo1: lda $1001 sta $2001 foo2: [...]