This is the Debugging Library, part of Kerberos Support Library. It provides the following APIs: AllocDebug memory leak tracking for C/C++ allocators Mac OS 9 only See AllocDebug.cp dprintf debugging console interface Mac OS 9 and Mac OS X See DCon.h Assert assertion dialogs Mac OS 9 only See Debug.Assert.cp DebugThrow debugging versions of C++ exceptions Mac OS 9 and Mac OS X see Debug.Throw.h The library build is divided into two parts: a static library and a shared library. This is a relic of the times when we were trying to release a source distribution of the library; the static library contains the bits of code we can't release to the public (for various reasons), whereas the shared library contains publishable code. The idea was the the source distribution would include the static library in binary form. Of course, we never got around to doing a source distribution... but the separation remains.