What is the NTX ID that Mt. Gox refer to in their Feb 17th Statement? Mt. Gox have released a statement concerning their recent withdrawal problems.


  In order to launch the new system, we are going through the following
  steps:
  
  
  Re-indexing the entire Blockchain (approx. 32 million entries)
  Fully deploying the new NTX ID
  Implementing a new bitcoin withdrawal queue that needs to be tested
  


Is the NTX ID something native to the Blockchain.info API? Does Blockchain.info host it's own separate version of the actual blockchain with additional meta data?
This is closely tied to the transaction-malleability bug, which allowed the re-posting of unconfirmed transactions with an altered transaction id. The issue increased the complexity for bookkeeping for services with a high number of transactions. Especially, some people used it to sneak duplicate withdrawals from Mt.Gox.

The change to the transaction ID was made by pushing additional zeros to the signature's front. I think NTX ID stands for normalized transaction id which will map all duplicate transactions back to the same representation, even when they were altered by exploiting the transaction malleability.

It is an internal blockchain representation used by Mt.Gox and has nothing to do with the service blockchain.info.