For Committee Members
||Provides a generic way to add higher level protocols on top of witness consensus
||Instructs the blockchain to attempt to sell one asset for another
||Used to cancel an existing limit order
||This operation can be used to add collateral, cover, and adjust the margin call price for a particular user
||This is a virtual operation that is created while matching orders and emitted for the purpose of accurately tracking account history, accelerating a reindex
||This operation can be used after a black swan to bid collateral for taking over part of the debt and the settlement_fund (see BSIP-0018)
||This is a virtual operation that is created while reviving a bitasset from collateral bids
Transaction Proposal Protocol
Echo allows users to propose a transaction which requires approval of multiple accounts in order to execute.
The user proposes a transaction using proposal_create_operation, then signatory accounts use
proposal_update_operations to add or remove their approvals from this operation. When a sufficient number of
approvals have been granted, the operations in the proposal are used to create a virtual transaction which is
subsequently evaluated. Even if the transaction fails, the proposal will be kept until the expiration time, at
which point, if sufficient approval is granted, the transaction will be evaluated a final time. This allows
transactions which will not execute successfully until a given time to still be executed through the proposal
mechanism. The first time the proposed transaction succeeds, the proposal will be regarded as resolved, and all
future updates will be invalid.
The proposal system allows for arbitrarily complex or recursively nested authorities. If a recursive authority
(i.e. an authority which requires approval of 'nested' authorities on other accounts) is required for a
proposal, then a second proposal can be used to grant the nested authority's approval. That is, a second
proposal can be created which, when sufficiently approved, adds the approval of a nested authority to the first
proposal. This multiple-proposal scheme can be used to acquire approval for an arbitrarily deep authority tree.
Note that at any time, a proposal can be approved in a single transaction if sufficient signatures are available
on the proposal_update_operation, as long as the authority tree to approve the proposal does not exceed the
maximum recursion depth. In practice, however, it is easier to use proposals to acquire all approvals, as this
leverages on-chain notification of all relevant parties that their approval is required. Off-chain
multi-signature approval requires some off-chain mechanism for acquiring several signatures on a single
transaction. This off-chain synchronization can be avoided using proposals.