84 Personal Content Experience: Managing Digital Life in the Mobile Age • Genre metadata that describes the place of a song in the ultra- fragmented fi eld of contemporary music, helping style-conscious listeners to maintain continuity; • Energy metadata that describes the power of the song to make the listeners move; • Appraisal metadata that gives the music fi gures of merit, for instance by their positions in download charts; • Hipness metadata that gives measures of the song’s current popular- ity and desirability among the consumers; this might differ from the appraisal; • Social metadata that links listeners to other people enjoying similar kinds of music. If we had to choose between these stereotyped “analytic” and “con- sumer” viewpoints, we would prefer the consumer view. We would like to achieve systems that allow content enjoyment, as opposed to content management. Of course, the analytic and technical views to metadata are needed in the machine room, but the users might prefer 19 to see just the more abstracted and domain-oriented metadata. Usually people are not well versed in information management, and are unable or unwilling to invest into the mental effort of classifying content into meaningful categories. We merely want either to receive our metadata pret-a-porter or have ways for our computers (and other devices) to fi ll in the metadata for us. Next we will discuss the two essential challenges related to all metadata management: 1. metadata creation (who creates it, how, and when?); and 2. metadata maintenance (checking its validity, updating metadata values when necessary, analyzing, and further processing metadata). 4.2 Metadata Creation Where does metadata come from? Somewhere, someone must have entered it. In the case of personal content, typically the owners of the content fi ll in their metadata. In the case of commercial content, 19 Of course, there are us tinkerers who enjoy taking things apart to see how they work. There will be people who spend hours tweaking metadata parameters to fi ne- tune some aspect of their content systems.