locale(3p)

NAME
locale - Perl pragma to use and avoid POSIX locales for built-in operations

SYNOPSIS
    @x = sort @y;       # ASCII sorting order
    {
        use locale;
        @x = sort @y;   # Locale-defined sorting order
    }
    @x = sort @y;       # ASCII sorting order again

DESCRIPTION
This pragma tells the compiler to enable (or disable) the use of POSIX locales for built-in operations (LC_CTYPE for regular expressions, and LC_COLLATE for string comparison). Each "use locale" or "no locale" affects statements to the end of the enclosing BLOCK.

See perllocale for more detailed information on how Perl supports locales.