How to specify 13(b9) chord

[RobDMax]

Hi, I trying out some jazz endings, variants on I VI II V I and I want a Bb7b913 or Bb713(b9) chord but I find I can't put a plain 13 b9 only a b13b9. How would you specify that without changing its value with something like Bdim7/Bb or G7b9/Bb for instance?
Thanks, Rob

 

[RobDMax]

Agh, to answer my own question you miss out the 7 so iReal accepts Bb13b9 but not Bb7b9 13

I should mention I'm notating some of the Jazz Endings in the very good article at: https://pianowithjonny.com/piano-lessons/7-beautiful-endings-for-jazz-tunes/