Token Metadata Standards

This document defines the JSON metadata schemas for tokens on the Mintlayer network.

• MLS01 — Fungible tokens
• MLS03 — Non-fungible tokens (NFTs)

---

Common top-level fields

All token metadata (both MLS01 and MLS03) shares these base fields:

Field	Type	Description
schema_version	string	Schema version, e.g. "1.0"
token_type	string	Discriminator — drives the shape of type_metadata
name	string	Human-readable token name
symbol	string	Ticker symbol
description	string	Short description
logo_uri	string	Image URI for the token logo
website	string	Official website
social	object	Social/community links (twitter, discord, telegram, github, whitepaper)
type_metadata	object	Type-specific fields — shape varies by token_type
cross_chain	array	Bridge/cross-chain contract addresses
market	object	Exchange listings, launch price, data feed IDs
certifications	array	Third-party certifications (Shariah, ESG, etc.)

---

MLS01 — Fungible Tokens

token_type values

Value	Description	Example file
utility	General-purpose utility or payment token	utility.json
stablecoin	Pegged to fiat, commodity, or crypto	stablecoin.json
wrapped	Wrapped representation of an asset from another chain	wrapped.json
governance	Token conferring voting rights over a protocol	governance.json
lp	Liquidity provider token from a DEX pool	lp.json
rwa	Real-world asset token	rwa-bond.json, rwa-real-estate.json, rwa-fund.json, rwa-stock.json, rwa-contract.json
memecoin	Community meme token — no utility, fair launch, renounced ownership	memecoin.json
commodity	Tokenized physical commodity — gold, silver, oil. Redeemable for delivery	commodity.json
carbon_credit	Fungible verified carbon offset batch. Carries vintage, methodology, retirement flag	carbon-credit.json
synthetic	Tracks external asset price via oracle. No ownership of underlying	synthetic.json
yield_bearing	Lending/staking receipt token that accrues interest. Exchange rate increases over time	yield-bearing.json
index	Market-cap-weighted basket of tokens with monthly rebalancing	index.json
fan_token	Sports club or creator token with voting on fan decisions and perks	fan-token.json
voucher	Merchant gift card / coupon redeemable for goods or services	voucher.json
insurance	DeFi coverage token against smart contract exploits, oracle failures, etc.	insurance.json

type_metadata by token type

stablecoin

• peg.currency — pegged asset (USD, EUR, XAU, BTC)
• peg.mechanism — fiat_backed | crypto_overcollateralized | commodity_backed | algorithmic | hybrid
• peg.collateral_ratio — e.g. 1.0 for fully backed
• peg.issuer — legal entity responsible for reserves
• peg.reserve_audit_url — link to reserve proof/attestation

wrapped

• underlying.chain — source chain (e.g. bitcoin, ethereum)
• underlying.symbol — original asset symbol
• wrapping_protocol — protocol managing the wrap/unwrap
• wrapping_ratio — e.g. "1:1"

governance

• governance.voting_mechanism — token_weighted | quadratic | 1_token_1_vote
• governance.quorum_threshold — minimum participation to pass a vote
• governance.proposal_threshold — minimum tokens to submit a proposal
• governance.timelock_days — delay before execution
• governance.dao_name / dao_url

lp

• pool.dex — DEX name
• pool.address — on-chain pool address
• pool.fee_tier — e.g. 0.003 for 0.3%
• pool.tokens — the two assets in the pair

commodity

• commodity.type — precious_metal | base_metal | energy | agricultural
• commodity.asset — e.g. gold, silver, crude_oil
• commodity.unit / units_per_token — e.g. troy_ounce, barrel
• commodity.grade / purity
• storage — custodian, locations, insurance, audit frequency
• redemption — minimum quantity, delivery fee, destination countries
• price_feed — oracle provider and oracle_uri (URL)

carbon_credit

• credit.unit — tonne_co2e
• credit.vintage_year / credit_type (avoidance | removal) / category (e.g. REDD+)
• project — name, VCS/Gold Standard ID, methodology, location, SDG goals, co-benefits
• registry — name, standard, serial range, verification body
• retirement — retired flag, beneficiary, reason — once retired a credit cannot be resold
• bridge — protocol used to bring the credit on-chain (e.g. Toucan)

synthetic

• tracks — asset name, ticker, exchange, ISIN, tracking_type, dividends_reflected
• price_feed — oracle provider, oracle_uri (URL), update frequency, circuit breaker deviation
• collateral — token, min/safe ratio, liquidation threshold and penalty
• risk_warnings — array of mandatory disclosures
• trading_hours — timezone, weekday window, weekend status

yield_bearing

• underlying — token symbol and address being deposited
• yield.apy_type (fixed | variable), current_apy, accrual_mechanism (rebasing | exchange_rate)
• yield.apy_oracle_uri — URL of the APY feed
• exchange_rate — current redemption rate and oracle_uri (URL)
• protocol — utilization rate, total supply/borrowed
• redemption — instant vs delayed, withdrawal fee

index

• index.methodology — market_cap_weighted | equal_weighted | liquidity_weighted
• components[] — symbol, address, weight
• rebalancing — frequency, mechanism (autonomous | governed), last/next date
• nav — oracle, current NAV in USD
• protocol.streaming_fee_annual — management fee
• issuance — mint/redeem contract

fan_token

• entity — type (sports_club | musician | brand), name, sport, league, country
• governance.voting_scope[] — list of decisions fans can vote on
• governance.voting_scope_note — disclaimer on scope limits
• perks[] — named benefits with descriptions
• supply — total supply, club reserve vs public split
• launchpad — platform, initial offering price/date

voucher

• issuer — legal entity issuing the voucher
• value — face_value_per_token, currency
• redeemable_for — description, categories, in_store/online flags
• acceptance.locations / countries
• expiry.expires — false for open-ended
• partial_redemption / combinable / refundable

insurance

• coverage.against[] — risks covered with descriptions
• coverage.covered_protocol — name, version, contract address
• coverage.limit_per_token_usd / payout_token
• validity — valid_from/until, cooldown period
• premium — annual rate, token, prepaid vs streaming
• claims — contract address, assessment body, payout delay
• pool — total/available capacity, utilization, capital provider APY
• exclusions[] — what is explicitly not covered

memecoin

• meme.origin / archetype (animal | person | object | phrase | original)
• launch.fair_launch, presale, team_allocation_pct, airdrop_pct
• contract.ownership_renounced, mint_disabled, blacklist_function, pausable
• liquidity.locked, lock_unlock_date, burned_lp_pct
• tax.buy_tax_pct / sell_tax_pct
• social — extended with tiktok, warpcast

rwa — fund sub-type (asset_class: "fund")

• fund.type — private_credit | private_equity | venture_capital | hedge_fund | money_market | real_estate_fund
• fund.vintage_year, investment_period_years, fund_life_years, extension_options
• manager — AUM, regulatory_status per jurisdiction
• terms — committed/called amounts, nav_per_token, management fee, performance fee, hurdle rate, carried interest
• liquidity.type (closed_end | open_end), lock-up, secondary market URL, distributions
• legal.administrator — fund admin entity

rwa — stock sub-type (asset_class: "equity")

• stock — company name, ticker, exchange, ISIN, CUSIP, tokens_per_share, sector
• rights.dividends — entitled, pass_through, payment agent
• rights.voting — typically false; note on proxy voting arrangement
• issuer_platform — the tokenization platform (separate from the SPV issuer)
• corporate_actions — splits, dividends, rights issues reflected flag
• valuation.price_feed_oracle_uri — URL of the real-time price feed

rwa — contract sub-type (asset_class: "receivable")

• contract.type — royalty_stream | lease | invoice | forward | service_agreement
• contract.reference, governing_law, effective_date, maturity_date
• counterparties — obligor (with credit rating), originator, SPV
• cashflows — total_face_value_usd, payment_frequency, minimum_guaranteed_annual_usd, royalty_rate_of_revenue, payment_schedule[], payment_waterfall[]
• risk_factors[] — explicit list of deal-specific risks
• valuation.method: "dcf" — discounted cash flow for contract assets

rwa

• asset_class — real_estate | bond | equity | commodity | fund | receivable | carbon_credit | ip
• legal — issuer, custodian, auditor, legal counsel (entity + jurisdiction + registration)
• jurisdictions — array of { country, regulatory_framework, token_classification, status }
• transfer_restrictions — KYC requirement, accredited-investor-only, geographic allow/blocklist, lockup
• rights — yield (fixed/variable), voting, redemption terms
• valuation — method, last value, frequency
• documents — array of { type, label, url, hash, date } — hash allows integrity verification

---

Cross-chain / bridge

"cross_chain": [
{
"chain": "ethereum",
"chain_id": 1,
"address": "0x...",
"standard": "ERC20",
"bridge_protocol": "Mintlayer Bridge",
"bridge_type": "canonical",
"verified": true
}
]

bridge_type:

• canonical — official deployment controlled by the token team
• bridged — third-party bridge, not controlled by the issuer
• wrapped — wrapped version with a different custodian

---

Market data

"market": {
"launch_date": "2024-01-15",
"launch_price_usd": 0.05,
"exchanges": [
{
"name": "Binance",
"type": "cex",
"pairs": ["MTK/USDT"],
"url": "https://...",
"listed_date": "2024-02-01"
},
{
"name": "Uniswap V3",
"type": "dex",
"chain": "ethereum",
"pairs": ["MTK/USDC"]
}
],
"coingecko_id": "mytoken",
"coinmarketcap_id": "12345"
}

---

Certifications

A general array for any third-party certification. The type field drives the optional shariah_details block.

"certifications": [
{
"type": "shariah",
"label": "Shariah Compliant",
"standard": "AAOIFI",
"certifying_body": {
"name": "Amanie Advisors",
"jurisdiction": "MY",
"website": "https://..."
},
"reference": "FATWA-2024-007",
"issued_date": "2024-03-01",
"expiry_date": "2025-03-01",
"review_frequency": "annual",
"status": "active",
"document_url": "https://...",
"document_hash": "sha256:...",
"shariah_details": {
"screening_standard": "AAOIFI",
"advisory_board": [
{ "name": "Sheikh ...", "institution": "..." }
],
"prohibited_activities_screened": ["riba", "gharar", "maysir", "haram_sectors"],
"purification_ratio": 0.02,
"purification_address": "...",
"sukuk_structure": "ijara"
}
}
]

Other supported type values: esg, halal, carbon_neutral, other.

---

MLS03 — Non-Fungible Tokens

token_type values

Value	Description	Example file
art	Digital artwork, 1/1 or limited edition	art.json
collection	Container NFT grouping other NFTs into an ordered series, gallery, strip, album, season, dossier, or portfolio	collection.json
collectible	Generative or curated collection (PFP, series)	collectible.json
gaming	In-game item, character, or land	gaming.json
rwa	Tokenized unique real-world asset	rwa-property.json
loyalty_points	Loyalty program points batch with expiry and redemption terms	loyalty-points.json
club_card	Membership card with tier, benefits, and access rules	club-card.json
video	Video NFT with production metadata and licensing rights	video.json
notification_legal	On-chain legal notice — court summons, regulatory service of process	notification-legal.json
ticket	Event access with seat, validity window, and resale rules	ticket.json
music	Audio NFT with master rights, royalty share, and physical companion	music.json
credential	Soulbound academic or professional qualification	credential.json
domain	On-chain domain name with multi-chain resolution records	domain.json
supply_chain	Physical product provenance record with stage-by-stage audit trail	supply-chain.json
pet_passport	Animal health and travel document — vaccinations, microchip, vet records	pet-passport.json
shariah_certificate	On-chain Shariah compliance certificate — institutional, product, fund, or transaction scope	shariah-certificate.json

type_metadata highlights (MLS03)

art — edition (number/total), medium (digital | physical_backed), ai_generated, license (CC0/commercial/personal/custom)

collection — collection_type (art_series | gallery | comic_strip | photography_series | anthology | curated), concept, curator (name, role, note), complete, series_order_significant, date_range, exhibitions[] (venue, country, year, section), press[], items[] (ordered list of member NFTs — each with order, token_id, name, image, description), bundle_policy (individual vs bundle pricing), provenance.mixed_custody

loyalty_points — program, points, points_unit, expiry_date, redeemable_for, transfer_policy, soulbound, rollover_policy

club_card — membership.program_name, tier, tier_hierarchy, member_since, valid_until, benefits[], transfer_policy, soulbound, kyc_required

video — media (duration, resolution, codec, audio tracks), production (director, ISRC, festival selections), edition, license (broadcast/streaming/theatrical rights, sublicensable)

notification_legal — notice_type, sender (court/regulator + jurisdiction), recipient, case (reference, type, subject), legal_basis (framework, article, on-chain recognition), timeline (served_at, response_deadline), acknowledgement_required

ticket — event (venue + coordinates, performance datetime), ticket (id, category, zone, seat, perks), validity (valid_from/until, used), resale (allowed, deadline, max price)

music — track (ISRC, ISWC, BPM, key), audio (master format, sample rate, bit depth), rights (master royalty share, sync licensing, streaming revenue share), physical_companion (acetate, claim deadline)

credential — credential_type, issuer (type, accreditation), holder, degree (title, field, ECTS, grade, thesis), verification (W3C VC standard, revocation registry), soulbound

domain — domain (full_name, tld, punycode), registration (expiry, auto_renew), resolution.records[] (ML/BTC/ETH/email/content/url), subdomains_enabled

supply_chain — product (sku, certifications), provenance_chain[] (stage, actor, location, coordinates, date, document_hash), current_custodian, redeemable, redemption (delivers_physical, shipping_destinations)

pet_passport — animal (species, breed, microchip_id), owner, passport (number, regulatory_framework, issuing_vet), vaccinations[] (disease, batch, valid_until), parasite_treatments[], health_certificates[], travel_history[], transfer_requires_vet_update

shariah_certificate — certificate_id (e.g. FDQ-2026-000412), scope (institutional | product | fund | transaction), methodology_version, standard (AAOIFI | IFSB | OIC_FIQH | custom), certifying_body (name, website, registry_address, jurisdiction), subject (type, name, registration_number, jurisdiction), certification_scope (areas[], product_categories[], geographic_coverage[]), screening (prohibited_activities_checked[], financial_ratios_checked, purification_required, purification_ratio), review_process (due_diligence_days, site_visit_conducted, scholars_count, approval_mechanism, evidence_hash, audit_trail_url), scholars[] (name, institution, chapter), multisig_approval (signatories_required, council_size, approval_transaction, approved_at), validity (issued_date, expiry_date, renewal_frequency, status), predecessor_certificate / predecessor_token_id (renewal chain — null for first issuance), documents[] (type: certificate | fatwa | due_diligence_report), soulbound: true

---

Additional base fields (MLS03 only)

Field	Type	Description
image	string	Primary media URI
image_mime_type	string	e.g. image/png, image/svg+xml
animation_url	string	Secondary media for video/audio/interactive
animation_mime_type	string	e.g. video/mp4, audio/mp3
external_url	string	Link to the asset's page on the issuer's site
attributes	array	Traits: [{ trait_type, value, display_type? }]
collection	object	{ name, description, symbol, image, total_supply }
creator	object	{ address, royalty_percentage, royalty_address }