what's a stable release?

[Karl Berry]

In gnulib-intro.texi, I noticed some text:

    We also make stable releases every two months, at
    @url{http://erislabs.net/ianb/projects/gnulib/}.

I wasn't aware this was being promulgated as an official release that
"we" make.

Anyway, what's stable about it?  As far as I was aware, Gnulib did not
promise any stability of anything at any level or make any attempt to do
anything special every two months.

That is, I thought these tarballs are essentially a snapshot taken for
the convenience of distro people, nothing more.

Thanks,
k