Cards

A card bundle is one memory card. Its header describes the card and nothing else; each save it holds is a bundle part carrying a complete save bundle.

What a writer has to regenerate to put those saves back on real hardware, and the numbers each format fixes, are in Memory Cards.

Header

shape is "card", and card is required: it is what makes the bundle one.

Key	Name	Req?	Notes
0	shape	yes	"card".
1	system	no	The system the card belongs to. A card is one system.
2	game	no	Only where every save on the card is for one game.
3	source	no	What read the card.
4	card	yes	The card’s format, capacity and system area.
5	description	no	Free-form note.
6	created_at	no	When the dump was assembled.

The header says nothing about any individual save. What a save is called, what it looks like and what game it is for are in that save’s own header, inside its nested bundle, where they stay correct once the save is sliced out.

Parts

One bundle part per save, plus whatever belongs to the card itself:

1SAV                                       the card
├── header  { shape: "card", system, card: { format, capacity, system_area } }
└── parts
    ├── kind "bundle"  slot 1, dirent, path, game hint
    │   └── 1SAV                           one save
    │       ├── header  { shape: "save", system, game, description }
    │       └── parts   one per file, each with its own slot and dirent
    ├── kind "bundle"  slot 2, ...
    └── kind "card-image"                  optional byte-exact archive

A save’s part carries the card’s record of that save, and only that:

Key	Name	Notes
3	path	The name the card’s directory holds, which tells two saves of one game apart.
4	slot	Its index in the directory.
5	dirent	Its directory entry, verbatim bytes.
2	role	Which socket the card was in, where that matters.
9	sha256	The inner bundle’s content hash, which is the save’s identity.

Card-level parts sit beside those: a card-image for a byte-exact archive of the whole medium, and aux for anything else binary that belongs to the card rather than to a save.

A card’s nested bundles are saves and nothing else. It holds no card, no device and no collection, which is what makes a card the last tier that nests: below it there are only a save’s own parts.

A save’s files are not parts of the card. They are parts of that save’s own bundle, which is required and not conventional: a save flattened into its card has no bundle to hash, and so no identity.

Extension keys

On a save’s part, describing the card’s record of it:

• x.1sav.dirent, when the directory dates the save and last wrote it.
• x.1sav.dirent.gc-mc and the other per-format keys, which decompose the entry so a writer can rebuild it.

x.1sav.label and x.1sav.icon go on the nested save’s own header instead, since they describe the save rather than the card. x.1sav.label MAY also be repeated on the part as an index copy, so a consumer can list the card without opening every payload.