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.