I guess winbox get it by using monitor command, but how to know it without interactive commands.
ros xxx.xxx.xxx.xxx "/interface/pppoe-server/print" "=.proplist=.id,name,user,service,remote-address" "?.id=*101D"
Status: re
Param 0: .id = *101D
Param 1: name = <pppoe-first.last>
Param 2: user = first.last
Param 3: service = company-pppoe
Param 4: remote-address = 00:23:CD:BE:8A:D8
Status: done
My interface query almost the same.
ros xxx.xxx.xxx.xxx "/interface/print" "?.id=*101D"
Status: re
Param 0: .id = *101D
Param 1: name = <pppoe-first.last>
Param 2: type = pppoe-in
Param 3: mtu = 1480
Param 4: bytes = 2201795/14914558
Param 5: packets = 12956/15366
Param 6: drops = 0/0
Param 7: errors = 0/0
Param 8: dynamic = true
Param 9: disabled = false
Param 10: running = true
Status: done
and finaly
ros xxx.xxx.xxx.xxx "/interface/pppoe-server/server/print" "=.proplist=.id,service-name,interface"
Status: re
Param 0: .id = *1
Param 1: service-name = company-pppoe
Param 2: interface = 7 My City
Status: re
Param 0: .id = *2
Param 1: service-name = company-pppoe
Param 2: interface = 8 My City
Status: re
Param 0: .id = *3
Param 1: service-name = company-pppoe
Param 2: interface = 9 My City
Status: done
I guess its possible by changing service-name, but its not an option for me.
Everything is fetchable by using internal id, except interface.
This is maybe not so usable information, but anyway i want to fetch it 
Any thoughts?