Is there really a conflict with the REXX "do" ?
As such not, but you may be one typo or error away from a possible disaster. On top of possible CMD.EXE processing mistakes, where DO is also a keyword: for %a in (*.TXT) do (do sort %a).
I'd suggest a new, unique name indeed, without suggesting a new name. For one because DO.EXE isn't an innocent tool which just prints a blank line.
FORMAT.COM/FORMAT.EXE and Rexx' Format() cannot be compared with DO. Format() is a function, which requires more than one typo or error to format a drive (if we ignore the "ARE YOU SURE?" dialog of the external OS command). DO is a different category, and a new command of your DO may make it worse.
I'm also not 100% sure, without testing, what the expected result of ...
/*TEST.CMD */; DO
... is. A syntax error of Rexx, or your DO explaining how it works.
IIRC I have DO in my path, but the arguments against such a name are valid and are more than trivial and theoretical, and nobody knows which commands may be introduced by you in the future. Despite of the fact that DO is a good name for what it is doing and how it works, you could consider a creative new name. DO is taken by CMD.EXE, and Rexx.
