linux cn_proc proc_event value is strange

Question

Hello I'm testing netlink socket

I create netlink socket and receive process event data. it works well.

But I faced something weird situations.

Received proc event value was "3"

In linux cn_proc.h process events defined

there is only 0x1, 0x2, 0x4 not 3 in definitions...

So I guess process event value 3 is result of bit-wise operation

PROC_EVENT_FORK & PROC_EVENT_EXEC ( 0x 0000 0001 & 0x 0000 0002 )

But I can't find any reference for proving my theory

Is there any knows about this issue?

Regards

Thanks