Add XRPL CAIP-19 specification for asset types (#158)

Author: bumblefudge

xrpl/caip19.md

@@ -0,0 +1,157 @@
+---
+namespace-identifier: xrpl-caip19
+title: XRP Ledger Namespace - Assets
+author: Pelle Braendgaard (@pelle)
+discussions-to: https://github.com/ChainAgnostic/namespaces/pull/158/
+status: Draft
+type: Standard
+created: 2023-02-23
+updated: 2025-11-06
+requires: ["CAIP-2", "CAIP-10", "CAIP-19", "CAIP-20"]
+---
+
+# CAIP-19
+
+*For context, see the [CAIP-19][] specification.*
+
+## Rationale
+
+The XRP Ledger supports multiple types of digital assets beyond its native XRP token.
+These include fungible tokens (issued currencies via trust lines), non-fungible tokens (NFTokens via XLS-20), AMM liquidity pool tokens, and the newer Multi-Purpose Tokens (MPTs). 
+This specification defines how to identify each asset type using the [CAIP-19] standard.
+
+## Asset Types
+
+The XRP Ledger has the following asset types:
+
+1. **Native XRP** - The native digital asset of the XRP Ledger, used for transaction fees and as a bridge currency
+2. **Trust Line Tokens (Issued Currencies)** - Fungible tokens issued by accounts, representing any asset (fiat currencies, commodities, other tokens)
+3. **NFTokens** - Non-fungible tokens following the [XLS-20] standard, representing unique digital or physical assets
+4. **AMM LP Tokens** - Liquidity provider tokens from Automated Market Makers (XLS-30), representing shares in liquidity pools
+5. **Multi-Purpose Tokens (MPTs)** - Next-generation fungible tokens with improved efficiency (currently in development)
+
+## Syntax
+
+The asset identification follows the CAIP-19 standard with the chain ID from [CAIP-2][] followed by a slash, an asset namespace, a colon, and an asset reference.
+
+```
+asset_id:           chain_id + "/" + asset_namespace + ":" + asset_reference
+chain_id:           See [CAIP-2][]
+asset_namespace:    "slip44" | "token" | "xls20" | "xls30" | "xls33"
+asset_reference:    slip44_ref | token_ref | xls20_ref | xls30_ref | xls33_ref
+
+slip44_ref:         "144"
+token_ref:          currency_code + "." + issuer_address
+currency_code:      standard_code | nonstandard_code
+standard_code:      [A-Za-z0-9?!@#$%^&*<>(){}[\]|]{3}
+nonstandard_code:   [0-9A-F]{40}
+issuer_address:     r[1-9a-hj-zA-HJ-NP-Z]{24,34}
+xls20_ref:          [0-9A-F]{64}
+xls30_ref:          [0-9A-F]{40} + "." + amm_address
+amm_address:        r[1-9a-hj-zA-HJ-NP-Z]{24,34}
+xls33_ref:          [0-9A-F]{64}
+```
+
+## Semantics
+
+### Native Asset (`slip44`)
+
+The native XRP token uses the SLIP-44 coin type as defined in [CAIP-20][].
+XRP has coin type 144 in the SLIP-44 registry.
+
+**Reference format:** `144`
+
+### Trust Line Tokens (`token`)
+
+Issued currencies on the XRP Ledger are fungible tokens that exist in trust lines between accounts.
+Each token is identified by a currency code and an issuer address.
+
+**Currency codes** can be:
+
+- **Standard format:** 3-character ASCII string (typically ISO 4217 codes like USD, EUR, but can include symbols)
+- **Nonstandard format:** 40-character (160-bit) hexadecimal string for custom identifiers
+
+**Reference format:** `{currency_code}.{issuer_address}`
+
+The currency code and issuer address are separated by a period (`.`).
+
+### NFTokens (`xls20`)
+
+NFTokens follow the [XLS-20] standard and are identified by their unique 64-character hexadecimal NFTokenID.
+The NFTokenID encodes multiple pieces of information including flags, transfer fee, issuer address, taxon, and sequence number.
+
+**Reference format:** `{nftoken_id}`
+
+### AMM LP Tokens (`xls30`)
+
+Automated Market Maker liquidity provider tokens (specified in [XLS-30]) represent ownership shares in AMM pools.
+LP token currency codes always start with `03` followed by 38 hex characters (a truncated SHA-512 hash of the asset pair).
+The issuer is the AMM account address.
+
+**Reference format:** `{lp_currency_code}.{amm_address}`
+
+### Multi-Purpose Tokens (`xls33`)
+
+Multi-Purpose Tokens (specified in [XLS-33]) are next-generation fungible tokens designed for improved efficiency.
+Each MPT is identified by a unique 64-character hexadecimal identifier.
+
+**Reference format:** `{mpt_id}`
+
+Note: MPTs are currently in development and not yet available on mainnet.
+
+## Test Cases
+
+```sh
+# Native XRP on Livenet
+xrpl:0/slip44:144
+
+# RLUSD issued currency on Livenet (Ripple USD stablecoin)
+xrpl:0/token:RLUSD.rMxCKbEDwqr76QuheSUMdEGf4B9xJ8m5De
+
+# USD issued by Bitstamp on Livenet
+xrpl:0/token:USD.rvYAfWj5gh67oV6fW32ZzP3Aw4Eubs59B
+
+# SOLO token with nonstandard currency code on Livenet (Sologenic)
+xrpl:0/token:534F4C4F00000000000000000000000000000000.rsoLo2S1kiGeCcn6hCUXVrCpGMWLrRrLZz
+
+# NFToken on Livenet
+xrpl:0/xls20:000B013A95F14B0044F78A264E41713C64B5F89242540EE208C3098E00000D65
+
+# AMM LP token on Livenet (XRP/TST pool)
+xrpl:0/xls30:039C99CD9AB0B70B32ECDA51EAAE471625608EA2.rE54zDvgnghAoPopCgvtiqWNq3dU5y836S
+
+# NFToken on Testnet
+xrpl:1/xls20:00081388C47ABB000CAFAF6F89F18D4E5F6A3377E340DA2C09999E250000001F
+
+# Multi-Purpose Token on Devnet (hypothetical - MPTs not yet on mainnet)
+xrpl:2/xls33:000000000A1B2C3D4E5F6789ABCDEF0123456789ABCDEF0123456789ABCDEF01
+```
+
+## References
+
+- [XRPL Tokens Documentation][] - Overview of token types on XRP Ledger
+- [XRPL Fungible Tokens][] - Trust line tokens and issued currencies
+- [XRPL NFTokens (XLS-20)][] - Non-fungible token standard
+- [XRPL AMM (XLS-30)][] - Automated market maker specification
+- [XRPL Currency Formats][] - Standard and nonstandard currency code formats
+- [NFToken Object][] - NFTokenID structure and encoding
+- [SLIP-44][] - Registered coin types for BIP-0044
+
+[CAIP-2]: ./caip2.md
+[CAIP-10]: ./caip10.md
+[CAIP-19]: https://github.com/ChainAgnostic/CAIPs/blob/master/CAIPs/caip-19.md
+[CAIP-20]: https://github.com/ChainAgnostic/CAIPs/blob/master/CAIPs/caip-20.md
+[XRPL Tokens Documentation]: https://xrpl.org/docs/concepts/tokens
+[XRPL Fungible Tokens]: https://xrpl.org/docs/concepts/tokens/fungible-tokens
+[XRPL NFTokens (XLS-20)]: https://xrpl.org/docs/concepts/tokens/nfts
+[XRPL AMM (XLS-30)]: https://xrpl.org/docs/concepts/tokens/decentralized-exchange/automated-market-makers
+[XRPL Currency Formats]: https://xrpl.org/docs/references/protocol/data-types/currency-formats
+[NFToken Object]: https://xrpl.org/docs/references/protocol/data-types/nftoken
+[SLIP-44]: https://github.com/satoshilabs/slips/blob/master/slip-0044.md
+[XLS-20]: https://github.com/XRPLF/XRPL-Standards/tree/master/XLS-0020-non-fungible-tokens
+[XLS-30]: https://github.com/XRPLF/XRPL-Standards/tree/master/XLS-0030-automated-market-maker
+[XLS-33]: https://github.com/XRPLF/XRPL-Standards/tree/master/XLS-0033-multi-purpose-tokens
+
+## Copyright
+
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).