+ use open ':locale';
+ use open IO => ':locale';
+
+and these
+
+ use open ':encoding(iso-8859-7)';
+ use open IO => ':encoding(iso-8859-7)';
+
+The matching of encoding names is loose: case does not matter, and
+many encodings have several aliases. See L<Encode::Supported> for
+details and the list of supported locales.
+
+When open() is given an explicit list of layers (with the three-arg
+syntax), they override the list declared using this pragma. open() can
+also be given a single colon (:) for a layer name, to override this pragma
+and use the default (C<:raw> on Unix, C<:crlf> on Windows).
+
+The C<:std> subpragma on its own has no effect, but if combined with
+the C<:utf8> or C<:encoding> subpragmas, it converts the standard
+filehandles (STDIN, STDOUT, STDERR) to comply with encoding selected
+for input/output handles. For example, if both input and out are
+chosen to be C<:encoding(UTF-8)>, a C<:std> will mean that STDIN, STDOUT,
+and STDERR are also in C<:encoding(UTF-8)>. On the other hand, if only
+output is chosen to be in C<< :encoding(koi8r) >>, a C<:std> will cause
+only the STDOUT and STDERR to be in C<koi8r>. The C<:locale> subpragma
+implicitly turns on C<:std>.
+
+The logic of C<:locale> is described in full in L<encoding>,
+but in short it is first trying nl_langinfo(CODESET) and then
+guessing from the LC_ALL and LANG locale environment variables.
+
+Directory handles may also support PerlIO layers in the future.
+
+=head1 NONPERLIO FUNCTIONALITY
+
+If Perl is not built to use PerlIO as its IO system then only the two
+pseudo-layers C<:bytes> and C<:crlf> are available.
+
+The C<:bytes> layer corresponds to "binary mode" and the C<:crlf>
+layer corresponds to "text mode" on platforms that distinguish
+between the two modes when opening files (which is many DOS-like
+platforms, including Windows). These two layers are no-ops on
+platforms where binmode() is a no-op, but perform their functions
+everywhere if PerlIO is enabled.