1. A method of searching a database for different types of digital assets, the method comprising: storing data in a memory that is read by a computer, the data comprising a server application program and only one single document type definition (DTD) for use in storing, retrieving, searching, or tracking at least three different types of digital assets stored in a single database, each digital asset of the digital assets including content and metadata, the metadata including rights management information, the server application program including modules for a parser, a query language utility, and a style sheet processor; receiving a demand containing user entered search parameters for information pertaining to the at least three different types of digital assets; accessing the DTD by executing the server application program, the DTD defining declared elements for the at least three different types of digital assets and defining elements and attributes for rights management of the at least three different types of digital assets, the at least three different types of digital assets including movies, photographs, and at least one of audio recordings, video recordings, promotional announcements, voiceovers, graphics, artwork, or text documents, wherein the rights management elements and attributes comprise metadata for at least one of: a contract identifier, an availability start date, an availability end date, an allowed number of plays per agreement, a copyright holder identifier, or a worldwide rights identifier, wherein the DTD defines metadata for movies and metadata attributes for the movie metadata, the movie-metadata attributes comprising at least one of: a definition for title, a definition for version, a definition for rating, a definition for minutes, a definition for release date, a definition for run time, a definition for color, a definition for synopsis, a definition for director, a definition for cast, or a definition for allowable usage of a movie, wherein the DTD defines metadata for photographs and metadata attributes for the photograph metadata, the photograph-metadata attributes comprising at least one of: a definition for black/white, a definition for color, a definition for caption, or a definition for legal restrictions; converting the demand into a query to be transmitted to the database by using the query language utility; searching the at least three different types of the digital assets in accordance with the converted demand and the accessed DTD; and converting search results returned from the database into a style sheet for input to a client application by using the style sheet processor.