Image data is returned if a request successfully completes, and if the request either does not include a req= command, or if req= has one of the following values: img, debug
The HTTP response MIME type is determined by fmt=
, or, if fmt=
is not specified, it depends on the value of attribute::Format
.
The HTTP response status is ‘200 OK’ if the request method was an unconditional GET
or HEAD
.
The server may reply with status ‘304’ (not modified) and not return any image data in response to a conditional GET
request (with the If-Modified-Since field present in the request-header
).