Must metadata be part of the object it describes, e.g., as “properties” of a Word Document or within tags of an HTML document?
In general, metadata is associated with a resource but need not be part of it. For example, an educational digital library may consist only of metadata records that point to resources. The resources exist external to the digital library and the metadata exists external to the resources. However, sometimes metadata exists as an integral part of a resource. Metadata should exist wherever applications or users that need it can find it. Sometimes, it is most useful to embed metadata within the resource itself. One common method is to embed metadata tags within the HTML markup of an electronically accessible resource. There are some advantages to this approach, not the least of which is that there is a presumption that the metadata is reflective of the version of the resource it describes. It also makes it convenient for consuming applications to retrieve the metadata implicitly. Another advantage is that when the resource is updated, the metadata is – at least presumably – updated as well.
