Prefix and Positional Authentication

Applications still use keyed relations and ordered sequences. Current Core implements these through opaque labels and descriptor-selected authentication layouts; it has no separate semantic Map/List adapters or compatibility APIs.

For the research framing, see MALT Abstraction. For application behavior, see the UnixFS model.

Prefix

A Prefix Root authenticates bindings at 32-byte coordinates. Its descriptor selects public coordinate derivation: SHA256 (profile 4) hashes opaque labels; Direct (profile 3) accepts a precomputed 32-byte coordinate. ArcTable preserves the original label and target. @payload is an ordinary label that UnixFS uses by application convention. Generic relation structures need no payload.

Positional

A Positional Root authenticates indexed targets, a count and an optional opaque payload CID. Only root slot zero stores metadata; all slots in non-root vectors hold content. For capacity 256, 255 elements fit in one vector; 256 elements require a root pointing to one full leaf vector. The count and capacity determine the tree shape, so height and per-node sizes are not stored.

Direct labels encode uint64 indices as exactly eight unsigned big-endian bytes; text such as "42" is not an index encoding. Core range queries use element indices. Applications verify the bytes referenced by the payload CID and interpret their own format. UnixFS uses a JSON document for chunk width and file size, then verifies chunk CIDs and slices bytes locally. Heterogeneous sequences need no byte-size fields.

Composition and updates

traversal follows an explicit array of label steps. A path query can end at another Root, a payload CID or a manifest CID; interpreting that target is application policy. Flat, hybrid and rooted UnixFS layouts are composed above these authentication primitives.

Retained writers import verified candidate state, apply changed bindings, and export candidate Roots for exact ordered batch materialization. A receipt does not authenticate a portable state transition or accept a trusted root.