D:\tmp>perldoc perlvar
NAME
    perlvar - Perl predefined variables

DESCRIPTION
  Predefined Names
    The following names have special meaning to Perl. Most punctuation names
    have reasonable mnemonics, or analogs in the shells. Nevertheless, if
    you wish to use long variable names, you need only say

        use English;

    at the top of your program. This aliases all the short names to the long
    names in the current package. Some even have medium names, generally
    borrowed from awk. In general, it's best to use the

        use English '-no_match_vars';