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The following terms are used throughout the documentation.


A persistent file addressed by public key and with lamport tracking its lifetime.

account owner

The address of the program that owns the account. Only the owning program is capable of modifying the account.


A front-end application that interacts with a Velas cluster.

bank state

The result of interpreting all programs on the ledger at a given tick height. It includes at least the set of all accounts holding nonzero native tokens.


A contiguous set of entries on the ledger covered by a vote. A leader produces at most one block per slot.


A unique value (hash) that identifies a record (block). Velas computes a blockhash from the last entry id of the block.

block height

The number of blocks beneath the current block. The first block after the genesis block has height one.

bootstrap validator

The validator that produces the genesis (first) block of a blockchain.

CBC block

Smallest encrypted chunk of ledger, an encrypted ledger segment would be made of many CBC blocks. ledger_segment_size / cbc_block_size to be exact.


A computer program that accesses the Velas server network cluster.


A measure of the network confirmation for the block.


A set of validators maintaining a single ledger.

confirmation time

The wallclock duration between a leader creating a tick entry and creating a confirmed block.

confirmed block

A block that has received a supermajority of ledger votes with a ledger interpretation that matches the leader's.

control plane

A gossip network connecting all nodes of a cluster.

cooldown period

Some number of epochs after stake has been deactivated while it progressively becomes available for withdrawal. During this period, the stake is considered to be "deactivating".


See vote credit.

cross-program invocation (CPI)

A call from one smart contract program to another. For more information, see calling between programs.

data plane

A multicast network used to efficiently validate entries and gain consensus.


An off-chain service that acts as a custodian for a user's private key. It typically serves to validate and sign transactions.


An entry on the ledger either a tick or a transactions entry.

entry id

A preimage resistant hash over the final contents of an entry, which acts as the entry's globally unique identifier. The hash serves as evidence of:

  • The entry being generated after a duration of time
  • The specified transactions are those included in the entry
  • The entry's position with respect to other entries in ledger

See Proof of History.


The time, i.e. number of slots, for which a leader schedule is valid.

fee account

The fee account in the transaction is the account that pays for the cost of including the transaction in the ledger. This is the first account in the transaction. This account must be declared as Read-Write (writable) in the transaction since paying for the transaction reduces the account balance.


When nodes representing 2/3rd of the stake have a common root.


A ledger derived from common entries but then diverged.

genesis block

The first block in the chain.

genesis config

The configuration file that prepares the ledger for the genesis block.


A digital fingerprint of a sequence of bytes.


An increase in token supply over time used to fund rewards for validation and to fund continued development of Velas.

inner instruction

See cross-program invocation.


The smallest contiguous unit of execution logic in a program. An instruction specifies which program it is calling, which accounts it wants to read or modify, and additional data that serves as auxiliary input to the program. A client can include one or multiple instructions in a transaction. An instruction may contain one or more cross-program invocations.


A public key and corresponding private key for accessing an account.


A fractional native token with the value of 0.000000001 vlx.


The role of a validator when it is appending entries to the ledger.

leader schedule

A sequence of validator public keys mapped to slots. The cluster uses the leader schedule to determine which validator is the leader at any moment in time.


A list of entries containing transactions signed by clients. Conceptually, this can be traced back to the genesis block, but an actual validator's ledger may have only newer blocks to reduce storage, as older ones are not needed for validation of future blocks by design.

ledger vote

A hash of the validator's state at a given tick height. It comprises a validator's affirmation that a block it has received has been verified, as well as a promise not to vote for a conflicting block (i.e. fork) for a specific amount of time, the lockout period.

light client

A type of client that can verify it's pointing to a valid cluster. It performs more ledger verification than a thin client and less than a validator.


A program with the ability to interpret the binary encoding of other on-chain programs.


The duration of time for which a validator is unable to vote on another fork.

native token

The token used to track work done by nodes in a cluster.


A computer participating in a cluster.

node count

The number of validators participating in a cluster.


See Proof of History.


A weighted credit in a rewards regime. In the validator rewards regime, the number of points owed to a stake during redemption is the product of the vote credits earned and the number of lamports staked.

private key

The private key of a keypair.


The code that interprets instructions.

program derived account (PDA)

An account whose owner is a program and thus is not controlled by a private key like other accounts.

program id

The public key of the account containing a program.

Proof of History

A stack of proofs, each which proves that some data existed before the proof was created and that a precise duration of time passed before the previous proof. Like a VDF, a Proof of History can be verified in less time than it took to produce.

public key

The public key of a keypair.


A block or slot that has reached maximum lockout on a validator. The root is the highest block that is an ancestor of all active forks on a validator. All ancestor blocks of a root are also transitively a root. Blocks that are not an ancestor and not a descendant of the root are excluded from consideration for consensus and can be discarded.


The component of a validator responsible for program execution.


Parallel smart contracts run-time.


A fraction of a block; the smallest unit sent between validators.

skipped slot

A past slot that did not produce a block, because the leader was offline or the fork containing the slot was abandoned for a better alternative by cluster consensus. A skipped slot will not appear as an ancestor for blocks at subsequent slots, nor increment the block height, nor expire the oldest recent_blockhash.

Whether a slot has been skipped can only be determined when it becomes older than the latest rooted (thus not-skipped) slot.


The period of time for which a leader ingests transactions and produces a block.

Collectively, slots create a logical clock. Slots are ordered sequentially and non-overlapping, comprising roughly equal real-world time as per PoH.

smart contract

A program on a blockchain that can read and modify accounts over which it has control.


The native token tracked by a cluster recognized by the company Velas.


Tokens forfeit to the cluster if malicious validator behavior can be proven.


2/3 of a cluster.


A synthetic account provided by the runtime to allow programs to access network state such as current tick height, rewards points values, etc.

thin client

A type of client that trusts it is communicating with a valid cluster.


A ledger entry that estimates wallclock duration.

tick height

The Nth tick in the ledger.


A digitally transferable asset.


Transactions per second.


One or more instructions signed by the client using one or more keypairs and executed atomically with only two possible outcomes: success or failure.

transaction id

The first signature in a transaction, which can be used to uniquely identify the transaction across the complete ledger.

transaction confirmations

The number of confirmed blocks since the transaction was accepted onto the ledger. A transaction is finalized when its block becomes a root.

transactions entry

A set of transactions that may be executed in parallel.


A full participant in a Velas network cluster that produces new blocks. A validator validates the transactions added to the ledger.


See verifiable delay function.

verifiable delay function

A function that takes a fixed amount of time to execute that produces a proof that it ran, which can then be verified in less time than it took to produce.


See ledger vote.

vote credit

A reward tally for validators. A vote credit is awarded to a validator in its vote account when the validator reaches a root.


A collection of keypairs that allows users to manage their funds.

warmup period

Some number of epochs after stake has been delegated while it progressively becomes effective. During this period, the stake is considered to be "activating". More info about: warmup and cooldown