Alphabetical list of terms commonly use in a NOCUST system with brief explanation.


Quick reference for researcher, implementers and people learning about the protocol.

Desired Properties

(desired characteristics / properties of protocol, effects if properties are violated)

Clear and concise explanation of the terms specific to NOCUST. For additional details, refer to the appropriate spec document.

Technical Specification


A user account in NOCUST is unique for a given parent-chain address and asset token address. The owner of the account is the person knowing the private key behind the parent-chain-address. The account can have several accounts for a given address for each asset token.

Asset token

Fungible token that comply with a token standard. The token should implement a standard interface for transfer function, transfer allowance function and balance function (ERC20 in Ethereum).


Period in number of blocks between each NOCUST commitment. Also called round.


Quarter of an eon.

Extended Epoch

Third of an eon.


Block number of the current eon.

Finalization (Swap)

A fully matched swap can be finalized. After the finalization the balances of the accounts involved are effectively credited and debited. The account is unlocked and the balances can be spent.

Finalization (Transfer)

A finalized transfer has its passive marker set to its actual value in the active tree. Previous to the finalization the passive marker is equal to 225612^{256} - 1. The finalization is required when the user wants to make a followup transfer or swap. This means that only the last transaction in the set of the active tree is no finalized.

Native asset token

Native token of the parent-chain used to pay transaction fees (Ether in Ethereum).


In the context of an interval tree, the offset of a leaf element is its left value. See specification of interval trees for a more detailed explanation.


Operator of the NOCUST system. Runs a dedicated server to facilitate off-chain transactions, process registrations, deposits and withdrawals. Has access to special method on the NOCUST smart-contract (contract owner). Submits checkpoints and is responsible to answer challenges.

Operator endpoint

Operator API used by the user to interact with the operator.

Passive Marker

The passive marker of a transfer is the left value or (offset)[#offset] of the last outgoing transfer in the passive interval tree of its recipient.


Frozen state of the commit-chain when the operator fails to reply a challenge or misses a checkpoint submission. No more operations are possible beside the user withdrawing their funds. Once in recovery, the commit-chain stays in this state indefinitely.


Required procedure in order to open an account at the commit chain.


Swap refers to a type of transaction involving 2 accounts of the same owner but of different asset token. One account is debited a certain amount and the other is credited a certain amount.


Unless specified otherwise, a transfer refers to a type of transaction involving a sender and a recipient (i.e simple money transfer across accounts).


Unless specified otherwise, transaction refers to a NOCUST transaction of type transfer or swap.


03.08.19 - Initial writeup

All content herein is licensed under GPL License.

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