Several Harry Potter films. Note: results of this query may change in the future when more films come available. Dave Cook's website offers reviews of children's films and the site is summarized in both RSS and ATOM feeds. Most of the films reviewed have an MPAA rating of G and/or British Board of Film Classification rating of U. This is declared in a rating for the channel as a whole. However, Dave includes reviews of some films rated PG-13 or 12 respectively which is declared at the item level and overrides the channel level metadata. The actual rating information comes from an online service operated by the relevant film classification board itself and is identified using a URL and human-readable text. The movie itself is identified by either an ISAN number or the relevant Internet Movie Database entry ID number. As with use case 2, trust is implicit given the source of the data, which is indicated by a link to Dave's site's policy. Separately, Fred combines Dave Cook's and other review feeds to provide alternative reviews of the movies by transforming the ATOM feeds into RDF and creating an aggregate view using SPARQL queries. Fred operates an antiracism education site which aggregates and curates content from around the Web. Fred wants to label the resources that he aggregates such that educational and other institutions may harvest the resources and associated commentary and metadata automatically for reuse within their instructional support systems, etc. One of the ways in which Fred wants to curate resources is to say about them that they are pedagogically useful but politically noxious. For example, some sites on the Web make claims about Martin Luther King, Jr that are motivated by a racist ideology and are historically indefensible. Fred's vocabulary allows him to claim that such resources are pedagogically useful for purposes of analysis, but that they are otherwise suspicious and should only be consumed by students in an age-appropriate manner or with appropriate supervision, etc. In other words, Fred needs to be able to make sharply divergent claims about resources: (1) that they are noteworthy, and (2) that they are, from his perspective, dangerous or noxious or troublesome. Mrs Chaplin teaches 7 year olds at her local school. An IT enthusiast, she makes her teaching materials available through her personal website. She adds metadata to her material that describes the subject matter and curriculum area. In order to gain wider trust in her work she submits her site for review by her local education authority and a trustmark scheme. Both reviewers offer Mrs Chaplin a digitally signed, machine-readable version of their trustmark that she can add to her site. She merges these into a single pool of metadata to which she adds content descriptors from a recognized vocabulary that declare the site to contain no sex or violent content. She adds her own digital signature to the metadata. The set of digital signatures allow user-agents to identify the origin of the various assertions made. As in use case 2, links from the content itself point to this metadata. Since the metadata is on the website itself, user agents are unlikely to take the assertions made in the metadata at face value. Unlike the trustmark operator, the local authority does not operate a web service that can support the label, it does, however, digitally sign its labels and publishes its public key on its website. This can be used to verify that it is indeed the local education authority that issued the relevant data in the label. Separately, a user-agent can interrogate the trustmark operator's database in real time to check whether Mrs Chaplin is authorized to make the assertions relevant to their namespace. Furthermore, the use of a recognized vocabulary for the content description means that a content analyser trained to work with that vocabulary can give a probabilistic assessment of the accuracy of the relevant data. Taken together, these multiple sources of data can provide confidence in the quality of the content and the local authority trustmark which is not directly testable. The multiple data sources may be further supported by recognising that Mrs Chaplin's work is cited in many online bookmarks, blog entries and postings to education-related message boards.