Can a PID be negative on Windows?

Question

I am writing a method that takes PID as parameter. Can it be a negative number on Windows? If it can't be I will add a negative check to my method. But I couldn't find information on the internet.

Answer 1

We only know they cannot be 0 or -1 (see Invalid thread and process IDs).

So don't depend on them being positive (or, multiples of four).