(BLES02252 being the European region code). Specifically, it likely refers to a "Super Patch" or "Option File" that updates the 2018 game with more recent transfers, kits, and league data.
Custom "eFootball" styled menus to replace the legacy UI. Technical Requirements & Installation superpsxcompes+2018bles02252eurgameall+upd
If you plan to publish this, here are a few blog post best practices from expert sources: (BLES02252 being the European region code)