I'm trying to get classification numbers for all a large number of patents through USPTO bulk download. The bulk download files come in three different formats--appended with ipg, pg, and pftaps respectively. I'm wondering how can I find the same patent classification number for all three formats. I don't really care if it is a US classification number or an international classification number, but when I find one type of classification number, I can't find the same type in a different format. The type of identifier in all three formats would be helpful as well. Thanks.
The US and EPO have gone to a unified patent classification system, the Cooperative Patent Classification (CPC). The USPTO recently reclassified all of the US patents to assign them a CPC classification. You can download a master file of all US patents with CPC classification at https://bulkdata.uspto.gov/data2/patent/classification/cpc/
I believe that is what you were requesting.