I'd like to have a$ implicitly structured like b$ (iol and xfa) when passed to the subroutine.
This would avoid sequences like the following and put more focus on what to do rather than having to deal with the technical background. Perhaps the syntax can be tweaked for this.
local dim workAddr$ : iol(addr1$)
workAddr$ = addr1$
gosub ADDR_2_FILE
workAddr$ = addr2$
gosub ADDR_2_FILE