$^O The name of the operating system under which this copy of Perl was built, as determined during the configuration process. For examples

$OLD_PERL_VERSION

$^C The current value of the flag associated with the -c switch. Mainly of use with -MO=... to allow code to alter its behavior

NAME

__DATA__ These keywords are documented in Special

$INPLACE_EDIT

$EFFECTIVE_USER_ID

$b Special package variables when using sort()

ne These operators are documented in perlop.

NAME