Todays multimedia content formats primarily encode the presentation of content but not the information the content conveys. However, this presentation-oriented modeling only permits the inflexible, hard-wired presentation of multimedia content. For the realization of advanced operations, the multimedia content has to be enriched by additional semantic information. To provide a basis for the semantic modeling of multimedia content in content sharing and collaborative applications, Enhanced Multimedia Meta Objects (EMMOs) and the query algebra EMMA were developed. Both provide a sound basis for...