question about labeled NFS+rfc7569+selinux

Hi folks,

I would like to know if somebody can comment on the following
regarding labeled NFS.

RFC 7569 talks about Label formats and specifically lists that "0" is
a reserved value.

Using labeled NFS with SElinux and looking at labels (in wireshark),
the selinux sends sends/sets label format as 0 (ie. this is a reserved
value according to the spec)

So we have labelformat_spec4 set to 0 where the spec says this field
"The LFS and the Security Label Format Selection Registry are
described in detail in [RFC7569]". It's unlikely that  "0" reserved
for Selinux and not explicitly specified there?

0 seems to be a good choice for using as a default label which the
RFC7862 vaguely talks about (though says nothing about the format for
a default label).

I'm not aware if Selinux is supposed to follow a spec and therefore I
don't think it is obligated to follow the rules of RFC 7569. Anybody
can comment how labeled NFS label format and SElinux label format
choice are supposed to co-exist?

Thank you.