kill -0 <pid> --- side effect or supported

[Dirk-Willem van Gulik]

I regularly use  'kill -0 <pid>' on FreeBSD as  a way to test if a certain process is still running (but without actually sending the signal). And I think it has worked reliably since the mid 80's.

Is it actually a properly supported use - as I recently happened to notice that it does not seem to be all that documented in kill(

Dw.