Ah ok if you want this there is an other way, you can create a file on your system e.g: owners.txt and add there the nicks that you want and use this code:

This code stop from any command if the user is NOT on the 'owners.txt' file.

Code:
ON *!:TEXT:!*:#: {
  var %rn = $read(owners.txt,ntw,$nick)
  if (%rn) && (%rn !== $nick) { halt }
}


Example of the 'owners.txt'

nick1
nick2
nick3
...

Need Online mIRC help or an mIRC Scripting Freelancer? -> https://irc.chathub.org <-