illumos gate

I think the idea is that its describing files and thus in 4. We mostly use 7 itself for non-driver kernel modules it seems. I think that it doesn't really fit that well anywhere, but either 7FS or just leaving it in 4 seems reasonable?

Well, my understanding is that 4 is 'file formats', fd doesn't describe any format, it talks about special files in /dev; if it doesn't fit in any subsection of 7 then let it just be in 7 itself (if we didn't use 7 for this, we can always start doing it if it seems logical).

I cite zero(7D) and null(7D) as supporting evidence this should be in section 7D.
intro(7) doesn't describe anything other than subsections.

     (7D)     The  system  provides  drivers  for  a  variety  of
              hardware  devices,  such  as  disk, magnetic tapes,
              serial  communication  lines,   mice,   and   frame
              buffers,   as  well  as  virtual  devices  such  as
              pseudo-terminals and windows.

              This section describes special files that refer  to
              specific  hardware  peripherals and device drivers.
              STREAMS    device  drivers  are   also   described.
              Characteristics of both the hardware device and the
              corresponding device  driver  are  discussed  where
              applicable.

Last attempt at being stubborn :-)

Albert Lee wrote:

I cite zero(7D) and null(7D) as supporting evidence this should be in section 7D.

intro(7) also reads "All device special files are located under the /devices directory.", /dev/zero and /dev/null are indeed links to /devices/, while /dev/fd/ contents aren't.

intro(7) doesn't describe anything other than subsections.

We could fix that :-)

[...]
Anything in (7) right now appears to either be X server drivers or leftover stuff from the BSD manpage section.

It also could be used for special cases like fd.