[Nut-upsuser] Is PIPEFN in upssched.conf necessary?

[Roger Price]

I'm looking at a Debian 11 box with upsd 2.7.4, but no upsmon running. The 
sockets for communication between upsd and the drivers are automatically 
declared in /var/run/nut :

  root at titan ~ ls -alF /var/run/nut
  drwxrwx---  2 root nut  140 Aug  7 15:57 ./
  drwxr-xr-x 30 root root 880 Aug  7 16:01 ../
  srw-rw----  1 nut  nut    0 Aug  7 15:57 dummy-ups-heartbeat=
  -rw-r--r--  1 nut  nut    5 Aug  7 15:57 dummy-ups-heartbeat.pid
  -rw-r--r--  1 nut  nut    5 Aug  7 15:57 upsd.pid
  srw-rw----  1 nut  nut    0 Aug  7 15:57 usbhid-ups-Eaton=
  -rw-r--r--  1 nut  nut    4 Aug  7 15:57 usbhid-ups-Eaton.pid

The attachment daemon upsd runs correctly with a custom management daemon. 
Shutdown and restart are ok. So why do I have to declare PIPEFN for the socket 
used between upsmon and upssched?  Why can't NUT automatically use the same 
directory as used for upsd?

Roger