We suppose that at first, %z is $null or 0, then the alias inc this variable in order to begin with the first lines until the last.
The else is here in order to reset the meter, if $0 is 0, it mean that the line we want doesn't exists because %z is the total number of lines in the file + 1.
58 is for $chr(58), the ":", look at /help tokenize
If $exists(texts\nick.txt) is $true, then the $read(texts\nick.txt,n,%z) should work.
