locale(3)

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

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

DDEESSCCRRIIPPTTIIOONN
       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.