Since this specific version (1.3.0) was a major update for Pokémon Shining Pearl ,
This patch added the logic to trigger the Arceus encounter. If you have a Pokémon Legends: Arceus save file with all main missions completed on your Switch, you can obtain the Azure Flute in your room in Twinleaf Town.
Addressed several "out of bounds" glitches and sequence breaks that were present in earlier versions (like 1.1.1). Sample "NFO" Style Description
It paved the way for the Member Card distribution, allowing players to access Newmoon Island to catch Darkrai.
A "piece" for a file like usually refers to a short technical description, a release note, or a "NFO" style summary used in gaming communities.