Raw

Defining a vocabulary instead of a DTD is the low-hanging fruit. (I'm deliberately using the term "vocabulary" instead of taxonomy or ontology to keep things simple, but the tools and techniques of those fields areas have much to contribute.) It doesn't reduce the work to do by simplifying it, but by reducing the scope: by forgetting about the data structures.

- Bob DuCharme

Not exactly snappy, but a very good point - and definitely applicable in the social data/dataportability arena.