How to abbreviate multiply -diminished or -augmented intervals

Question

I know they aren't used often, but how do you abbreviate a doubly-, triply-, or otherwise multiply- diminished or augmented intervals? For instance, a perfect fifth is abnbreviated P5, a diminished fifth is d5, what is a doubly-diminished fifth? What about a quintuply diminished fifth (rare, esoteric, probably never has been or will be used? Yes; but sensical? Yes it is).

I was assuming either stacking them, like dd5 and AAA5 (but this gets cumbersome after a while), or prefixing the number behind it, like 2d5 and 3A5. I'm leaning towards the later because it is much more compact and manageable, but:

1. Does that conflict with some other kind of notation that could possibly be mixed up with it?
2. Would an experienced musician understand what it denotes?

For context, I'm writing some code that works with intervals, so I want it to be completely generic: my program shouldn't break just because somebody wants to use qradruple flats and 6-degree diminished intervals or something.

Answer 1

The standard notation I've seen is just to keep writing degree signs before the numerical interval for multiply diminished and plus signs for augmented. Your abbreviated version doesn't conflict with anything I've seen, bit I wouldn't immediately recognize it either. Just +++++5 for quintuply-augmented fifth. I think the use of d and A can be a little confusing since those are letter names, but I know lots of basic theory books use them. In my experience, more advanced theory texts use degree and plus signs.