We just had an internal discussion if this is allowed or not.
This discussion arose after chasing a bug where in Pro Tools parameter automation in latch mode was messed up when a parameter set another parameter during the change callback so that the other parameter being set already cleared the inParameterChangedCallback flag that should avoid infinite parameter setting loops.
Although I got the feeling that this is just something that shouldn’t be done, I don’t find a clear statement on that in the docs. And I wonder why Pro Tools is the only host where we found this bug, is there a difference between AAX and the other formats?