Meaning of delete change_type and affect on dataset url

[rufuspollock]

The change_type: "delete" case is interesting. Is this used for datasets that no longer exist in the catalog? What is the appropriate server response for the corresponding URL? If the URL should return a record, how should the response record indicate the dataset is deleted? If it shouldn't return a record, should it instead return a response code 410 (Gone)? Should the URL still be included as a field in these cases?