This indicates the file is the core game, not an update or DLC.
When a download is split into parts (like .part1.rar , .part2.rar , etc.), the files work as a single unit. P5-S-NSwTcH-[BASE]-NSP-(eShop)-Ziperto.part4.rar
This is a digital game format used for the Nintendo Switch. This indicates the file is the core game,
A modified Switch running Atmosphere.
Do not rename individual parts. They must have the exact same name except for the part number. P5-S-NSwTcH-[BASE]-NSP-(eShop)-Ziperto.part4.rar