What do you mean about "bindings are absent"?

Most of this stuff, in particular availability, is not documented directly for a reason. So for instance Tie::Hash::NamedCapture is used to implement named captures. It is loaded automagically by the internals when you do a $+{foo} style lookup. It uses a bunch of the re:: functions, which are exposed via universal because they are then compiled into the core executable and thus do not require an additional library to be loaded. Now I could have implemented the entire thing without using any perl level modules or exposing any subs, but that would have limited the options available to the programmer which I felt was not the Perl way.