Advanced Intelligent Corruption Handling
An extra hash that is an SHA1 hashes of 180 Kb block to prevent corruption. AICH prevents that a single bad byte (due to bad clients/bad memory) leads to corruption of 9.28 MB chunk. It will allow to recover the corrent 180kb blocks of a chunk.
AICH hashes are stored in a hashtree. The roothash of this can be added to an ed2k link.
AICH supersedes the Defeat 0 Filled Part Senders feature