Aside: for my own self respect, I want to make some sort of disclaimer here
(with maybe several points): I'm sure that sometimes I post things that do
any of (1) make other people cringe (for one reason or another), (2) make me
look uninformed (or worse), and (3) other causes for embarrassment (to myself
of others).
I finally realized that the "normal" progression / hierarchy of the Debian
releases is from Unstable to Testing to Stable.
I never looked it up -- I assume that, like most people, we don't look up
everything but make assumptions based on past experience. I expected that the
normal progression for Debian releases would be from Testing (trying all / any
kind of new, possibly weird things), to Unstable (concentrating on things that
survived some initial testing and now maybe being released to a select group
for some real pounding en route to Stable.
(I've never used anything other than stable releases, so my misunderstanding
hasn't had any real world effect on my systems, but I have been confused at
times, and suspect that maybe one other person out there may have similarly
been confused.)