DISCIPLINE can be either of C<:raw> for binary mode or C<:crlf> for
"text" mode. If the DISCIPLINE is omitted, it defaults to C<:raw>.
Returns true on success, C<undef> on failure. To mark FILEHANDLE as
-UTF-8, use C<:utf8>, and to mark the as bytes, use C<:bytes>.
+UTF-8, use C<:utf8>, and to mark it as bytes, use C<:bytes>.
The C<:raw> are C<:clrf>, and any other directives of the form
C<:...>, are called I/O I<disciplines>. The C<open> pragma can be
C<require> or C<use> statement, $evaltext contains the text of the
C<eval EXPR> statement. In particular, for an C<eval BLOCK> statement,
$filename is C<(eval)>, but $evaltext is undefined. (Note also that
-each C<use> statement creates a C<require> frame inside an C<eval EXPR>)
-frame. C<$hasargs> is true if a new instance of C<@_> was set up for the
-frame. C<$hints> and C<$bitmask> contain pragmatic hints that the caller
-was compiled with. The C<$hints> and C<$bitmask> values are subject to
-change between versions of Perl, and are not meant for external use.
+each C<use> statement creates a C<require> frame inside an C<eval EXPR>
+frame.) $subroutine may also be C<(unknown)> if this particular
+subroutine happens to have been deleted from the symbol table.
+C<$hasargs> is true if a new instance of C<@_> was set up for the frame.
+C<$hints> and C<$bitmask> contain pragmatic hints that the caller was
+compiled with. The C<$hints> and C<$bitmask> values are subject to change
+between versions of Perl, and are not meant for external use.
Furthermore, when called from within the DB package, caller returns more
detailed information: it sets the list variable C<@DB::args> to be the