Here is a brief description of the model number system for PUMA.
Model numbers for all PUMA knives have four digits. In the case of folding knifes, the first digit is always zero. In 1987 PUMA added two digits before the model number, making it a six digit number to designate what type of knife and material was used to make the knife. By looking at the first two digits of the new model numbering system you can tell a lot of information about the knife.
You need to combine the Type and Material to get the first two digits of the model number. Listed below is the prefix digit system used. Click on the document to enlarge it.