You are viewing the version of this documentation from Perl blead. This is the main development branch of Perl. (git commit 20aecbd6fc571b7f8365b05efb9d4113ba36aa06)
IO::Handle->format_formfeed(EXPR)
$FORMAT_FORMFEED
$^L

What formats output as a form feed. The default is \f.

You cannot call format_formfeed() on a handle, only as a static method. See IO::Handle.