That would be in the language files.
If youre using 1.7.18 then you can uncomment UseStrictPrivMsg and the restart services and they'll display as /nickserv instead of /msg NickServ which saves you the trouble of editing the language files and causing problems.
When you then try and use /msg NickServ COMMAND you get the following response:
[12:20:33] -NickServ(
services@your-irc.net)- "/msg nickserv" is no longer supported. Use "/msg nickserv@services.your-irc.net" or "/nickserv"
instead.
Which tells you to use the same format that the /nickserv and similar aliases use.