The C<flags> value will normally be zero; if HV_ITERNEXT_WANTPLACEHOLDERS is
set the placeholders keys (for restricted hashes) will be returned in addition
to normal keys. By default placeholders are automatically skipped over.
-Currently a placeholder is implemented with a value that is literally
-<&Perl_sv_undef> (a regular C<undef> value is a normal read-write SV for which
-C<!SvOK> is false). Note that the implementation of placeholders and
+Currently a placeholder is implemented with a value that is
+C<&Perl_sv_placeholder>. Note that the implementation of placeholders and
restricted hashes may change, and the implementation currently is
insufficiently abstracted for any change to be tidy.