D#07 means D#o7 whereby the o should be written like a degree sign: uppercase!
If I copy it from this link it is written normally, I know how to type it in word, but in SE it doesn't work:
D#o7 = D#°7 = dim7, stands for diminished seventh chord: root, min 3rd, dim 5th, dim 7th
The notes of D# dim7 are D#,F#,A,C
As you can see it is related to the B 9 chord - without root tone.
every (vii o7) can be considered as a (V b9) without root and like the B+7 is probably a secondary dom. 7b9 chord to e-minor the 5th of this chord can be augmented for both progressions: D# dim7 and B7 => B +7 (the + is related to the fifth and means B 7 (#5)