5.8.5 linux  <                    => unix perlio
5.8.5 linux  <            binmode => unix perlio
5.8.5 linux  <:raw                => unix 
5.8.5 linux  <:raw:perlio         => unix perlio

5.8.6 darwin <                    =>             stdio
5.8.6 darwin <            binmode =>             stdio
5.8.6 darwin <:raw                => unix
5.8.6 darwin <:raw:perlio         => unix perlio

5.8.6 win32  <                    => unix        crlf
5.8.6 win32  <            binmode => unix        crlf
5.8.6 win32  <:raw                => unix 
5.8.6 win32  <:raw:perlio         => unix perlio

##</code><code>##

$ perl -v
This is perl, v5.8.5 built for i386-linux-thread-multi
--snip--

$ perl -MPerlIO -le 'open IN, "<"            ,"a.txt";             print for PerlIO::get_layers(IN)'
unix
perlio

$ perl -MPerlIO -le 'open IN, "<"            ,"a.txt"; binmode IN; print for PerlIO::get_layers(IN)'
unix
perlio

$ perl -MPerlIO -le 'open IN, "<:raw"        ,"a.txt";             print for PerlIO::get_layers(IN)'
unix

$ perl -MPerlIO -le 'open IN, "<:raw:perlio" ,"a.txt";             print for PerlIO::get_layers(IN)'
unix
perlio

##</code><code>##

$ perl -v
This is perl, v5.8.6 built for darwin-thread-multi-2level
--snip--

$ perl -MPerlIO -le 'open IN, "<"            ,"a.txt";             print for PerlIO::get_layers(IN)'
stdio

$ perl -MPerlIO -le 'open IN, "<"            ,"a.txt"; binmode IN; print for PerlIO::get_layers(IN)'
stdio

$ perl -MPerlIO -le 'open IN, "<:raw"        ,"a.txt";             print for PerlIO::get_layers(IN)'
unix

$ perl -MPerlIO -le 'open IN, "<:raw:perlio" ,"a.txt";             print for PerlIO::get_layers(IN)'
unix
perlio