Linklist software is an API for a doubly linklist.
For a more complete description see the May 1998 issue of the Linux Journal (version 1.0.0) and for the current version see the Postscript and html documentation in the package.
The original source for the documentation is now in LaTeX.
Not much to say here, the package is fairly easy to compile and use. Read
the docs for how to use the API. The INSTALL file explains how to compile
and install/uninstall the package.
When new code is compiled it will link to libdll.so, and when a program
executes it will look for libdll.so.1. This is why they are sym-linked
to libdll.so.1.2.0 the current version.