California written discovery generally consists of four methods: Request for Production of Documents, Form Interrogatories, Special Interrogatories, and Requests for Admissions. Responses to California discovery requests are not continuing: the responding party only needs to respond with the facts as known on the date of the response, and is under no obligation to update its responses as new facts become known. This causes many parties to reserve one or two interrogatories until the closing days of discovery, when they ask if any of the previous responses to discovery have changed, and then ask what the changes are. California depositions are not limited to one day, and objections "must" be made in detail or they are permanently waived. A party may only propound thirty-five written special interrogatories on any other single party unless the propounding party submits a "declaration of necessity". No "subparts, or a compound, conjunctive, or disjunctive question" may be included in an interrogatory. However, "form interrogatories" which have been approved by the state Judicial Council do not count toward this limit. In addition, no "preface or instruction" may be included in the interrogatories unless it has been approved by the Judicial Council; in practice, this means that the only instructions permissible with interrogatories are the ones provided with the form interrogatories.