one-story, double-story, three-story g?

What’s the common practice and the logic for naming the different possible shapes of a and g in the English language?
From what I could gather, the common practices seems to be to have two groups: the single-story shapes and the double-story shapes. But until now, I fail to see the formal logic behind that.
If I take the double-story a and turn it upside down, I then get, what is referred to as single-story shape of the g – even though this is exactly the same shape. So what actually are then the “stories” of that character?

Therefore my personal logic would be to name the different possibilities:
single-story a
double-story a
double-story g (because it is basically an upside down double-story a)
and three(!)-story g

But maybe I am missing something …

I've always liked “binocular” for two-storied g’s, although “pince-nez” would be a closer simile.

But logic? Forget about it, this is type!

Indeed, let's not get hung up on topoterminology.

I used to call the binocular "g" bicameral, but then
Kent convinced me that terms is better reserved
for writing systems (as in UC and lc). But I'll never
call it "two-storied"!

hhp

I call it a "split-level" g

What about onefold, twofold, threefold?

Don’t forget about the four-storey gee!
http://flickr.com/photos/hardwig/2524903281/

If we had a clear definition what the story of a letter is, then calling a shape a four-story g would be no problem.

Nick: Binocular / monocular makes sense for the g, but not so much for the a.

Ack! That's gotta be end of story!

Call it the sexy curvy letter!

It could be a g.

A better question is where did the single story g come from?

Ralf's original question can be explained away by extending the metaphor. Think of the baseline as ground level. A two-story building has two floors above ground level; you don't count the basement if it has one.

I think I've identified the best clear way to describe the two main types of g without running into exceptions. The verticals of letters such as b, d, p, q are stems. Any g whose tail drops down from the right side is a stemmed g, and others such as the typical binocular g are unstemmed.

I like "the sexy, curvy letter". If you've practised calligraphy you'll know that that g feels so good when you get it right; and usually, if you don't get it right, you know it's not right soon after you've started the lower curve.

And when you get a typographic "g" right it feels so good forever! :-)

hhp