Metadata? Thesauri? Taxonomies? Topic Maps! "Topic maps are organized around topics, which represent subjects. That is, in a topic map you find topics. Every topic you find represents a subject out in the real world that it is a symbol or stand-in for in the topic map. The definition of subject is essentially "anything whatsoever". What this means is that from the point of view of a topic map, objects are just a special kind of subject.
What this means is that the whole machinery we have created to describe the concepts in a subject-based classification is also available to describe the objects being classified. Thus, we can create a topic type for objects ("document", perhaps), and express the metadata using names, occurrences, and associations. The topic types let us keep track of what is a document and what is a concept, but we no longer need different technologies for metadata and classification.
And once we have everything in a single representation we can start to cross the boundaries by for example describing the authors of a paper further, and connecting them with the terms from the subject-based classification. Effectively what has happened is that the straightjacket has been removed, and we can now say anything we want to. The technology is no longer the limiting factor; instead the limits are set by our imagination and by how much information we are able to maintain within the economic constraints of our projects."