[Rd] source definition for R_NilValue/return from TYPEOF(R_NilValue)

[Dan Kortschak]

Hello,

for reasons I want to know the return value of TYPEOF(R_NilValue), I
expect it to be NILSXP, but I can't find this documented anywhere.
Ideally, I'd like to see the source definition of R_NilValue, but after
fair bit of searching I cannot find an obviously location for this.

Would someone please point me in the right direction?

thanks
--
CRICOS provider code 00123M