Hi Noel,

It's just a triad, and in BB it is recognized as just Ddim, ( or F dim, Ab dim, or try B dim) or , if you would like to include the b in it, as Ddim7, but Ddim will do for you.
When you say b5 you are - it's about coventions-implying a seventh, but you are not typing it.
BB will not recognize it.
I know what you mean- not being a PC-, and I hope that I as a more or less human being understood your question and could be of any help.

This will do, I think, but when you want to know more:
Ddim in fact could be a sustitute for G7b9, Bb7b9, C#7b9 or E7b9, and as such it is not really a VII'th of the scale, just the upper tensions of a dominant, as dicovered in jazz by C.Parker, but much earlier by Handel with Umlaut.

A real VII'th would be the Dmin7b5, which includes the c, something completely different.