HepPDT contains the fixed data about each particle type. In other words, it contains the data that can be found in the Review of Particle Properties.
This data is conceptually split into particle information (e.g. mass) and decay information.
HepPDT Version 1 has the ability to call decay methods directly from the decay channel information. This, however, has been deemed too heavy for general use.
HepPDT version 2 provides a simple set of particle data classes. By request, the particle ID translation methods are decoupled from the HepPDT classes and can be linked directly from the HepPID library. HepPID is part of the HepPDT package, which is now being maintained on the CERN Savannah website.
HepPDT version 3 is further simplified, and contains no decay information. In addition, it is possible to customize how ParticleDataTable deals with unknown particle ID's (e.g., the requested ID does not have a matching entry in the ParticleDataTable). This version is also available from the CERN Savannah website.