156 Personal Content Experience: Managing Digital Life in the Mobile Age At the Exit/Export phase (“S” in GEMS), when the content leaves the mobile device, composer components assume an important role. Like harvesters, these components know what kind of metadata can be included in the content object in question, but while harvesters read metadata, composers write it. Composers read the metadata associated with the exiting content from our metadata database and write into the fi le whatever metadata can be embedded into it. For example, an ID3 tag composer will write into MP3 fi le all music related metadata from the database. Similarly, EXIF and IPTC tags are written by respec- tive composers into the JPG fi les. Upon exiting, the composers may need to exclude some metadata associated with the outbound content object. A typical reason is that the framework is capable of processing metadata that cannot be included in standard metadata scheme, such as associations in MP3 fi les. Also, some metadata may have been tagged as private: for example, the user may not wish to expose the shooting location of certain photos. Each metadata attribute has extra information describ- ing whether that metadata can or cannot be exported or sent out of the system. Of course, our framework can handle a much wider variety of metadata than can be expressed in EXIF or ID3 tags. For instance, as discussed above, all relationships will be lost. In a similar manner, most of the context information does not fi t into tags, at least in any standard way. There are a few exceptions, such as EXIF image metadata format (section 4.6), that contains fi elds for location information in the form of GPS coordinates. Some content types, such as text notes, will not allow any embed- ded metadata in the fi rst place. In these cases, our framework can produce a separate fi le, called metadata manifest, containing any meta- data that cannot be embedded into the content fi le. It can also include any relationships that make sense to export. Of course, if you are sending just one photo to your friend, there is not much sense in adding any relationships into the metadata manifest, since the recipient may not have those other items forming the relationship. On the other hand, if you are sending your playlists with the songs, or you have sent other images previously, it might be benefi cial to send the relationship information, too. Then the recipient will know how the new content objects relate to the old ones. There is no widespread standard for metadata manifests. As a con- sequence, our metadata manifest works only between two devices using our own metadata framework. We hope and believe that there will be a widely accepted standard in coming years. Already there are