> For the complete documentation index, see [llms.txt](https://bsv.brc.dev/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bsv.brc.dev/wallet/0164.md). # Output Identity Tags for BRC-100 Wallets David Case () ## Abstract This specification defines a **tag convention** for [BRC-100](/wallet/0100.md): an output tag prefix `id:` that carries a stable list key for a held output. Callers use it with ordinary `listOutputs` tag filters. It does not change the BRC-100 request or response shape, and it does not require special wallet storage behavior beyond normal tags. ## Motivation Basket profiles and applications often need a stable handle for one wallet output — reload after restart, target a spend, correlate UI to storage — without scanning every row. Stamping that handle as a normal, **queryable** tag under a short prefix makes `listOutputs` the lookup API, without new BRC-100 fields or pseudo-tag peel paths. ## Specification ### Tag form This specification uses tags of the form: ``` id: ``` * The prefix is exactly `id:` (lowercase, ASCII). * `` is a non-empty string chosen by the writer that stamps the tag (wallet or tool). * Because reference BRC-100 clients commonly **trim and lowercase** tags before store and match, writers SHOULD use a case-insensitive alphabet for `` (e.g. lowercase hex or decimal digits), and readers MUST treat tag equality as case-insensitive. Tags beginning with `id:` are used for this output list-key role. ### Meaning * `id:` identifies a **held output row** for list and spend targeting inside that wallet storage. * It is **not** a global asset id, token id, origin, outpoint, remittance field, or proof of ownership. * Encoding of `` is defined by the writer (e.g. decimal storage primary key, UUID). Only that writer must round-trip it. * Uniqueness: `` SHOULD be unique among that wallet’s held outputs (or a documented narrower scope such as per basket). * Stability: for a given held row, `id:` SHOULD remain stable for the life of that row (including unproven / unmined outputs if they are listable). ### Behavior `id:` is an ordinary BRC-100 output tag. No special `listOutputs` semantics, peel, inject, or foreign-tag overwrite is required of generic wallet storage. Conforming **tools and wallets that adopt this profile** SHOULD: 1. Stamp `id:` on the output when the row is created or first taken into custody (same path as any other tag). 2. Query with a full `id:` tag via ordinary `tags` / `tagQueryMode`. 3. Treat `id:` as their own list key vocabulary — not as token id, origin, or on-chain identity. Basket profiles that need those notions use their own tags (e.g. `bsv21:`, `origin:…`). Applications MAY read `id:` from `listOutputs` (with `includeTags`) and reuse it in later filters or app state. ### Out of scope * Changing BRC-100 method schemas or WalletWire encodings * Basket names, token economics, or provenance proofs * Requiring a particular key generation algorithm (UUID, counter, storage PK encoding, …) * Mandating peel/inject or other non-tag storage paths in reference wallets ## Security considerations * **Not authentication** — Knowing `id:` only helps address a row inside a wallet that already authorized `listOutputs` / spend for that basket. * **Authority** — The tag is only as trustworthy as the storage that stamped it. Counterparty remittance is not a substitute for the holding wallet’s (or tool’s) own stamp. * **Case folding** — Assume tags are lowercased in storage; do not put case-sensitive secrets in ``. * **Ambiguity** — `id:` is short and may appear in other informal tag sets. Writers that need a stricter namespace MAY document a longer key form; this BRC does not reserve exclusivity of the two-letter prefix beyond the list-key meaning above for adopters. ## References 1. [BRC-100](/wallet/0100.md) — Unified Open BSV Wallet-to-Application Interface 2. [BRC-37](/outpoints/0037.md) — Basket and Custom Instructions Extension for Bitcoin Outpoints 3. [BRC-46](/wallet/0046.md) — Wallet Transaction Output Tracking (Output Baskets) 4. [BRC-153](/wallet/0153.md) — Action Reference Labels for BRC-100 Wallets 5. [BRC-147](/tokens/0147.md) — 1Sat Ordinals Basket Profile --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. 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