What does use open mean in this context? Should I just put a line that says "use open;" in my code? I've never heard of the open module.

PhilHibbs runs 'perldoc open' and reads it

Update: I tried putting use open ':bytes'; in, but that fails:
Unknown PerlIO layer class ':bytes' at C:\bin\hexdump.cmd line 10

Update: I tried putting use open ':utf8'; in, but that makes no difference, it still only outputs 0A for a line-end if the file name is a parameter, but 0D 0A if it's piped or redirected in.

Update: It's just clicked - this is what tye is talking about in his reply above.