Nikon D500 Professional Technical Manual page 49

The following table shows how Custom Settings d4 and f1
combine for flexible camera control using the shutter-re-
lease button ("SRB") and the button to which Sync. release
selection has been assigned ("custom control"):
Custom Setting
f1 > Sync.
d4 release selection
Master release
only
Sync
Remote release
only
Synchronized
release
No
sync
Remote release
only
Shutter released by
SRB alone
Master Remote
SRB + custom control
Master Remote
49