BIP: 122
  Title: Transaction Version 2 Specification (wildcard inputs)
  Author: Chris Priest 
  Status: Draft
  Type: Standards Track
  Created: 2015-11-30
==Abstract== This specification defines a new type of transaction that supplements (not replaces) version 1 transactions. ==Motivation== Version 1 Bitcoin Transactions have one large inefficiency: When you want to spend from multiple inputs with the exact same scriptPubKey, you have to list the same signature multiple times. This bloats the transaction size and makes it expensive to spend from small value inputs. Because small value inputs are expensive to send, they remain in the UTXO pool which full nodes have to keep around. It is believed that long term increase of the UTXO set can have negative scaling consequences on the network. ==Specification== A version 2 transaction is formulated the exact same way as a version 1 transaction with one exception: each input is treated as a "wildcard input". A wildcard input beings the value of all inputs with the exact same scriptPubKey in a block lower or equal to the block the wildcard input is confirmed into.