226 IM Used
226 IM Used response status, in the context of delta encodings, is a status code set by the server to indicate that it is returning a delta to the GET request that it received. IM stands for Instance Manipulations, the term used to describe an algorithm generating a delta.
With delta encoding a server responds to
GET requests with differences (called deltas) relative to a given base document (rather than the current document). The client uses the
A-IM: HTTP header to indicate which differencing algorithm to use and the
If-None-Match: header to hint the server about the last version it got. The server generates a delta, sending it back in an HTTP response with the
226 status code and containing the
IM: (with the name of the algorithm used) and
Delta-Base: (with the
ETag matching the base document associated to the delta) HTTP headers.