I found this on Wikipedia.
The Bebop blues(Spitzer 2001, 62):
I7 IV7 I7 v7 I7 IV7 ♯IVo7 I7 V/ii♭9 ii7 V7 I7 V/ii♭9 ii7 V7
I can't parse the
V/ii♭9 chord symbol. What notes is this made up of?
V/ii denotes the (secondary) dominant (V) of the supertonic (ii).
In the key of C major this would refer to the (secondary) dominant of the supertonic Dm, which is an A major chord. Adding the b9 gives you A(add b9), but I suppose - especially since it is a jazz blues - a dominant 7 must be inferred and thus it is an A7(b9) chord, with the notes A, C#, E, G, Bb. (It is actually exemplified as A7(b9) in the wikipedia article although it is never stated that the example belongs to C major.) I believe that the correct notation should be V7(b9)/ii.
This is very reasonable since with the V/ii you'll find that you're dealing with standard turnarounds in the chord progression.
The whole chord progression in C becomes:
| C7 | F7 | C7 | G7 C7 | | F7 | F#º7 | C7 | A7(b9) | | Dm7 | G7 | C7 A7(b9) | Dm7 G7 |
Another way of denoting this chord function would be VI7(b9). However since VI indicates a major chord which is not a member of the diatonic functions, it is instead traditionally analysed as a secondary dominant of the supertonic, i.e. V7(b9)/ii.
In traditional functional roman numeral analysis a slash is used to denote a harmonic function in relation to a diatonic note or chord. Note that this has nothing to do with slash chord notation!
Can't say I've come across it before, written that way, but, in C, it could be G7 with a flat 9. with a D bass, played D-G-B-D-F-Ab, but not necessarily in that order, except the D bass.The Ab should be an octave above the low G, otherwise there is a clash, and it wouldn't be a b9.
Love the term 'parse'!!