Hi Albert, Thanks for the info. I am aware of the pid+ctime trick. Whist I agree the odds of a pid being re-used in the same microsecond are practically impossible, clearly unique id was created for a reason. I guess I was taken by the unique id function. It's a more elegant solution to the problem. It has been in Darwin in an almost unaltered form since 2013 with a comment saying /* This structure is API */. So I guess my question remains - is there any other way to access this, and if not, is it possible to request that this become public api? It's already implemented and has tests, it really just needs to be moved to a public header. thanks nick

Thanks Albert - I opened FB22652617