Global flag that enables system calls made by Perl to use wide character APIs native to the system, if available. This is currently only implemented on the Windows platform.
This can also be enabled from the command line using the -C switch.
The initial value is typically 0 for compatibility with Perl versions earlier than 5.6, but may be automatically set to 1 by Perl if the system provides a user-settable default (e.g., $ENV{LC_CTYPE}).
The bytes pragma always overrides the effect of this flag in the current lexical scope. See bytes.