A Come and Go Proof Token (CnG PToken) is an Asset present in a UTXo which if used in the input of a Tx must be replaced at the same address where it was taken from.
This property must be guaranteed by the Home Address Script at which the CnG PToken can be found.
When guaranteeing that an a soon to be inserted node (yet to be minted) is Valid the Minting Policy can make use of a CnG PToken found in the HEAD of the list to assess if the list exists or was correctly minted.
CnG PTokens can also record State and State change. Due to their unlocking being controlled by the Home Script, additional logic can be integrated to check for the change of Datum attached to the UTXo or burning and re-minting with a different TokenName.
