The request was effective yet the encased payload has been changed from that of the source server’s 200 OK reaction by a changing proxy.
This status code enables the intermediary to tell beneficiaries when a change has been applied, since that information may affect later choices with respect to the substance. For instance, future reserve approval demands for the substance may just be relevant along a similar requestway (through similar intermediaries).
The 203 reaction is like the Warning code of 214 Transformation Applied, which has the benefit of being applicable to reactions with any status code.
A 203 reaction is cacheable as a matter of course; i.e., except if generally demonstrated by the strategy definition or express store controls.