XRB and network economics

#Supply

• Fixed supply. 500 million XRB, fully issued at genesis across published allocations. No inflation.
• Burn ceiling. Lifetime burns are capped at 40 percent of supply, 200 million XRB. Every charge is scaled by a pure integer function of total supply, replayed identically by every validator, so cumulative burn approaches and can never exceed the ceiling.
• Supply floor. Circulating supply never falls below 300 million XRB, and per-action charges scale down as supply falls.

#The mandatory fee path

All chargeable actions are priced in XRB and settled by burning it. Fees are denominated in the token and set by protocol, so per-action costs are uniform and predictable. There are four charge classes:

1. Execution fees. Per-instruction charges metered by execution receipts. The free T0 envelope is sized to a single basic operation, so simple token transfers stay free for any user; complexity, composition and bulk state growth are what pay.
2. Subnet anchoring rent. A monthly charge per subnet validator plus a charge per registered checkpoint, burned as part of checkpoint registration.
3. Value-based settlement fees. A small basis-point fee on value settled by a batch settlement call, in place of instruction charges that would misprice a workload of few, large transactions.
4. Capacity licences. Deployment above the free tier needs a staked fuel position in tiers of 50, 500 and 5,000 XRB. For partner institutions the foundation stakes the tiers as revocable, time-boxed delegations, so banks do not need to buy and hold the asset.

#Execution receipts

Every execution produces a receipt recording instructions executed, peak call depth, cross-contract calls and net storage written. One opcode is one instruction; there is no per-opcode gas table, which keeps replay deterministic and cheap. Nested calls share one budget and one receipt.

#How XRB secures routed value

• Standing is bought, continuously, with burned XRB. A subnet routes only while it holds a current checkpoint, and every checkpoint burns anchoring rent. A lapsed checkpoint is lapsed standing.
• Attesting validators are bonded. The validator seats that attest a cross-subnet settlement hold staked and vested XRB that governance can revoke.

The right to move value across the network, and the integrity of the record that it moved, both reduce to XRB that has been burned or staked.

#Validator emissions

Validators are compensated from a fixed pool of 40 million XRB, released per Bitcoin block. There is no block subsidy and no inflation beyond the pool. The schedule is front-loaded: five epochs of 45,000 Bitcoin blocks (about ten months each), with the per-block rate halving at each boundary.

About 52 percent of the pool is emitted in epoch 0, and the pool is exhausted at the end of epoch 4, in early 2031. After that, emissions are zero and validator compensation comes from a share of network service fees.

Emissions accrue only to accredited validator seats, divided each block by attested activity: published and co-signed state roots, verified replay participation and uptime attestations, with a cap on any one seat's weight. Seat grants to institutional partners vest on published, multi-year milestone schedules.