Most common polymers have standardized abbreviations. Matweb has a page that provides a list of most of those abbreviations ===>HERE<===
A short snippet of the list is included so you can see what it looks like.
PA Polyamide (Nylon) PA Polyacrylate PAE Polyarylether PAEK Polyaryletherketone PAI Polyamide-Imide PAMS Poly(Alpha Methylstyrene) PAN Polyacrylonitrile PARA Polyarylamide (polyaramide) PAS Polyarylsulfone PASA Polyamide, Semi-Aromatic (Nylon) PASU Polyarylsulfone
Other information included in the molding mark usually includes the manufacturer, the cavity number and information regarding when the part was molded. That way, problems can be traced back to specific cavities for tool work or performance issues can be sorted for on the basis of when discrepant material was molded.