What does PET12/PA15/LDPE mean for standup pouch package

When some customers reach the flexible converter for the packages for their products, especially windshield washer fluids, liquid laundry detergent, fabric softner, liquid soap products, and the supplier may make the price quote against PET12/PA15/LDPE. What does that mean? If the customer does not ever source the standup pouch package before, he may get confused with the price sheet, especially