Great, where do I need them to be defined? 
I have set Hostname, system knows the current firmware and date/time on Mikrotik.
On my PC’s running Debian, when I backup my Firefox browser settings I execute:
tar -cvf BackUp_Firefox_$(hostname)_$(date +%Y%m%d-%H%M%S).tar -P ~/.mozilla/firefox/
so I guess, same approach does not work on MikroTik …
Executing the:
/export file=“$HOSTNAME_$FIRMWARE_$DATE-$TIME”
would result in file:
13 __-.rsc script 23.9KiB feb/08/2021 11:00:55