open -h(uuuh?)

On windows we have start for launching documents and applications. On gnome we have gnome-open which opens documents and applications. On the mac we have the 'open' command. Open -a launches the specified application (based on the app paths). Open on it's own launches a document with the registered preferred application. Then there's 'open -h'.

% open -h unistd.h
unistd.h?
[0]	cancel
[1]	all

[2]	/System/Library/Frameworks/Kernel.framework/Headers/libsa/unistd.h
[3]	/System/Library/Frameworks/Kernel.framework/Headers/sys/unistd.h
[4]	/usr/include/sys/unistd.h
[5]	/usr/include/unistd.h

Which header(s) for "unistd.h"? 5

It opens up header files. I mean WTF?