RE: Null filename ("") is considered to correspond to an existing, readable, and writable file?

[Drew Adams]

    In my previous reply, I forgot that read-file-name returns "" if the
    user exits with empty input (and _not_ the DEFAULT-FILENAME arg).  So
    your real question is why read-file-name does that, a rather different
    question from the one you asked.

No, my question is not about read-file-name. Please, drop the lessons on how
to code commands that read file names. I can do that; trust me.

My point was that the doc for a function should describe its arguments.
That's all.

This is especially true for functions that have names that can suggest they
return a different result from what they do return in one particular case.

I've made my point. You don't want to hear it. Maybe it's not important to
anyone. Let's move on.