I status ignored does not require updating
Intended to prevent the 'lost update' problem, where a client GETs a resource's state, modifies it, and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict. Common causes are a server that is down for maintenance or that is overloaded.Note that together with this response, a user-friendly page explaining the problem should be sent.
This response is sent on an idle connection by some servers, even without any previous request by the client.
The request has been received but not yet acted upon.
It is noncommittal, since there is no way in HTTP to later send an asynchronous response indicating the outcome of the request.
Clients are expected to remove their caches and links to the resource.
The HTTP specification intends this status code to be used for "limited-time, promotional services".
Either may be used whether there is a single values list or multiple lists, and regardless of the number of values per list.