RGB-20: Fungible assets

LNPBP: 0020
Aliases: RGB20
Vertical: Smart contracts
Title: RGB fungible assets interface (RGB-20)
Authors: Dr Maxim Orlovsky <orlovsky@lnp-bp.org>,
         Giacomo Zucco,
         Marco Amadori,
         Nicola Busanello,
         Federico Tenga,
         Armando Dutra,
         Zoe Faltibà,
         Sabina Sachtachtinskagia,
         Martino Salvetti
Comments-URI: <https://github.com/LNP-BP/LNPBPs/discussions/140>
Status: Proposal
Type: Standards Track
Created: 2019-09-23
Updated: 2023-07-24
Finalized: ~
Copyright: (0) public domain
License: CC0-1.0






Asset information

Asset ownership


  • secondary issue

  • issue delegation

  • cancelling issue

Burning & replace

Proof of reserves


Interface specification is the following Contractum code:

-- Defined by LNPBP-31 standard in `RGBContract.sty` file
import urn:ubideco:stl:6vbr9ZrtsD9aBjo5qRQ36QEZPVucqvRRjKCPqE8yPeJr#choice-little-boxer as RGBContract

interface RGB20
    -- Asset specification containing ticker, name, precision etc.
    global spec :: RGBContract.DivisibleAssetSpec

    -- Contract data and creation date is separated from the spec since it must
    -- not be changeable by the issuer.
    global data :: RGBContract.ContractData
    global created :: RGBContract.Timestamp

    -- State which accumulates amounts issued
    global issuedSupply+ :: RGBContract.Amount
    -- State which accumulates amounts burned
    global burnedSupply* :: RGBContract.Amount
    -- State which accumulates amounts burned and then replaced
    global replacedSupply* :: RGBContract.Amount

    -- Right to do a secondary (post-genesis) issue
    public inflationAllowance* :: Zk64
    -- Right to update asset Specification
    public updateRight?

    -- Right to open a new burn & replace epoch
    public burnEpoch?
    -- Right to burn or replace existing assets under some epoch
    public burnRight*

    -- Ownership right over assets
    private assetOwner* :: Zk64

    genesis       :: spec
                   , data
                   , created
                   , issuedSupply
                   , reserves {RGBContract.ProofOfReserves ^ 0..0xFFFF}
                  -> assetOwner*
                   , inflationAllowance*
                   , updateRight?
                   , burnEpoch?
                  -- errors which may be returned:
                  !! supplyMismatch
                   | invalidProof
                   | insufficientReserves

    op Transfer    :: previous assetOwner+
                   -> beneficiary assetOwner+
                   !! nonEqualAmounts

    -- question mark after `op` means optional operation, which may not be  
    -- provided by some of schemata implementing the interface

    op? Issue      :: used inflationAllowance+
                    , reserves {RGBContract.ProofOfReserves ^ 0..0xFFFF}
                   -> issuedSupply
                    , future inflationAllowance*
                    , beneficiary assetOwner*
                   !! supplyMismatch
                    | invalidProof
                    | issueExceedsAllowance
                    | insufficientReserves

    op? OpenEpoch  :: used burnEpoch
                   -> next burnEpoch?
                    , burnRight

    op? Burn       :: used burnRight
                    , burnedSupply
                    , burnProofs {RGBContract.ProofOfReserves ^ 0..0xFFFF}
                   -> future burnRight?
                   !! supplyMismatch
                    | invalidProof
                    | insufficientCoverage

    op? Replace    :: used burnRight
                    , replacedSupply
                    , burnProofs {RGBContract.ProofOfReserves ^ 0..0xFFFF}
                   -> future burnRight?
                    , beneficiary assetOwner+
                   !! nonEqualAmounts
                    | supplyMismatch
                    | invalidProof
                    | insufficientCoverage

    op? Rename     :: used updateRight
                   -> future updateRight?
                    , new spec


This standard is the first fungible token interface defined for RGB assets, so compatibility with other standards do not apply.

The standard provides a superset for ERC20 token capabilities; however due to RGB nature it is not directly compatible with ERC20 and other similar standards using account-based blockchains (and not client-side-validation on UTXO chains). However, a ERC20 tokens may be re-issued or bridged under this standard.


Include from

Reference implementation




This document is licensed under the Creative Commons CC0 1.0 Universal license.

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