Thanks for your question. The DFM rules included with FAB 3000 are simply generic rules to meet the standard guidelines of most PCB manufacturers (most of these values are based from PCB manufacturer requirement in the Silicon Valley area).
Note: Truthfully DFM rule values really depend on the technology you're using (such as Flex/RF/Rigid, copper thickness, # of layers, etc.) and most importantly the PCB manufacturer you choose. For best results, you should consult with your PCB manufacturer and receive their recommended DFM rules. Those rules can be implemented directly into FAB 3000 using the DFM Rules Management (menu: Tools / DFM / Rules Management...). Whether or not IPC (or another organization) has set standard default values for DFM Rules (which I have not seen), it's the PCB manufactures rules your design must adhere to.