[ros-users] Design decisions behind libTF...?

Dear all,

I am interested in knowing what exactly was behind the _design_ of the tf
library, but all that I can find is
<https://code.ros.org/trac/wg-ros-pkg/browser/pkg/trunk/libTF/doc/libTF_Manual.tex?rev=175>
This is basically a document about the library's features and how to use
it, but is there somewhere else more information about _why_ libTF was made
the way it is...?

Herman