Unsets the NV/IV status of an SV.
=for apidoc Am|U32|SvOK|SV* sv
-Returns a U32 value indicating whether the value is an SV. It also tells
-whether the value is defined or not.
+Returns a U32 value indicating whether the value is defined. This is
+only meaningful for scalars.
=for apidoc Am|U32|SvIOKp|SV* sv
Returns a U32 value indicating whether the SV contains an integer. Checks
=for apidoc Am|bool|SvTRUE|SV* sv
Returns a boolean indicating whether Perl would evaluate the SV as true or
-false, defined or undefined. Does not handle 'get' magic.
+false. See SvOK() for a defined/undefined test. Does not handle 'get' magic.
=for apidoc Am|char*|SvPVutf8_force|SV* sv|STRLEN len
Like C<SvPV_force>, but converts sv to utf8 first if necessary.