Motivation for renaming configure.in to configure.ac and its effect?

[Steffen Dettmer]

Hi,

I'm trying to understand the motivation for renaming configure.in
to configure.ac. If I remember correctly it was related to the
fact that ./config.status or whoever else processes .in files.

I goggled but was unable to find it.

If this is the motivation and no `effects' depend on the file
name, I think it might not be worth to rename configure.in files
in old projects, because when working with CVS (or other VCS that
do not handle renaming well) and when having to maintain old
branches. When renaming such a file, after cvs update make will
fail for the developers (and they need to rerun autoreconf and
configure).

Is the renaming configure.in to configure.ac cosmetic only and
is it safe to keep configure.in in old projects/branches?

oki,

Steffen