PDB (Brookhaven Protein Databank format) files.
The PDB files can be directly viewed by (a helper application) Rasmol or by a plug-in Chime.
In the Microsoft site it says " The .PDB extension stands for "program database." It holds the new format for storing debugging information that was introduced in Visual C++ version 1.0. In the future, the .PDB file will also hold other project state information. One of the most important motivations for the change in format was to allow incremental linking of debug versions of programs, a change first introduced in Visual C++ version 2.0. "
maybe this helps.....
