2f123fd8.pnach -

In many emulation circles, files are named by their CRC to ensure the patch is applied to the correct region (e.g., the NTSC-U version vs. the PAL version).

The filename 2f123fd8.pnach appears to be a (likely for a specific PS2 game title) — but without knowing which game it belongs to or what you want to do, I’ll give you a general guide on developing a .pnach file from scratch. 2f123fd8.pnach