Input

实际是个普邓森见证。

和输出的关系：当前输入，就是上一区块的输出。

A reference to an output being spent by a transaction.

/// The input for a transaction, which spends a pre-existing unspent output.
/// The input commitment is a reproduction of the commitment of the output
/// being spent. Input must also provide the original output features and the
/// hash of the block the output originated from.

• OutputFeatures # 来源标记。来自普通交易，还是 Coinbase？根据来源不同，成熟时间不同。
• Commitment # 之前输出的 Commitment

/// A transaction input.
///
/// Primarily a reference to an output being spent by the transaction.
#[derive(Serialize, Deserialize, Debug, Clone)]
pub struct Input {
    /// The features of the output being spent.
    /// We will check maturity for coinbase output.
    pub features: OutputFeatures,
    /// The commit referencing the output being spent.
    pub commit: Commitment,
}

An input must provide -

• the commitment (to lookup the output in the MMR)
• the output features (hash in output MMR dependent on features|commitment)
• a merkle proof showing inclusion of the output in the originating block
• the block hash of originating blocks
  • [tbd - maintain index based on merkle proof?]