Quoting Roger Mills <[log in to unmask]>:

> I found an old msg. of Trebor Jung's concerning this terminology, which was
> never properly answered, and got to wondering:
> Are things like [aj] [oj] [iw] etc. (Vowel +glide) called "falling
> diphthongs"?  I believe they are.
> Converserly, then, [ja] [jo] [we] are called "rising" diphthongs, I believe.
> AIUI, it's the Vowel > glide vs glide > vowel makeup that's the determining
> factor, rather than the articulatory positions of the vowel/glide
> components. One could, after all, envision diphthongs with _central/low_
> glides-- [i_@, @_o]; Thai IIRC has diphthongs like [1_a] (high central V +
> low glide).
> What say you all? In particular, what says Trask's Dictionary, or the other
> one that's often cited (whose author I disremember).

That's the normal usage. I could quote something, but that'd be in German or

I'll note that calling a diphthong like [aj] "falling" because it goes from low
to high would be most deliciously evil!