On Mon, Oct 19, 2015 at 3:01 PM, Christian Decker via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
As with the previous version, which was using a hard-fork, the normalized transaction ID is computed only considering the non-malleable parts of a transaction, i.e., stripping the signatures before computing the hash of the transaction.

Is this proposal recursive? 

Coinbase transaction

* n-txid = txid

Non-coinbase transactions

* replace sigScripts with empty strings
* replace txids in TxIns with n-txid for parents

The 2nd step is recursive starting from the coinbases.

In effect, the rule is that txids are what they would have been if n-txids had been used right from the start.