Collections

A collection bundle is several cards and saves in one file. It is how one file spans systems, and it is the only shape with nothing of its own to say.

Header

shape is "collection". system, game and card are all forbidden, because a collection describes no single system, no single game and no card: each of those belongs to an entry.

Key	Name	Req?	Notes
0	shape	yes	"collection".
3	source	no	What assembled it.
5	description	no	Free-form note.
6	created_at	no	When the collection was assembled.

Parts

Every part is a bundle part, one per entry, and each entry is a complete bundle of any shape but another collection: a save, a card or a device. A collection is the one shape that does not nest inside itself, which is what stops the format recursing without end.

1SAV                                       shape "collection"
└── parts
    ├── kind "bundle"  system "psx"        a card
    │   └── 1SAV  { shape: "card", card: { format: "ps1-mc", … } }
    │       └── parts   kind "bundle" per save
    ├── kind "bundle"  system "ps2"        another card, different system
    │   └── 1SAV  { shape: "card", card: { format: "ps2-mc", … } }
    └── kind "bundle"  system "gb"         a plain save, no card in between
        └── 1SAV  { shape: "save", game: { … } }

Entries need not be the same shape. A collection can hold a PS1 card, a PS2 card and a loose Game Boy save side by side, and a consumer reads each entry’s own shape to know which it has.

The outer part’s system and game repeat what the entry’s own header says, so a consumer can list a collection from the head region without opening payloads. They are an index: producers SHOULD keep them consistent, and the inner header wins on a mismatch.

What a collection may hold

Any shape but another collection, which is the one rule that keeps the format from recursing. A collection holds devices, cards and saves; a device holds cards and saves; a card holds saves; a save holds nothing nested. Follow that chain and it always ends, so how deep a bundle goes is a consequence of the shapes in it rather than a number this spec has to fix.

Two cards out of the same console are one collection of two card bundles. Two consoles’ storage in one file is a collection of two devices.