Is HTML structured or unstructured information?

Is HTML structured or unstructured information?

"Structured information may be characterized as information whose intended
meaning is unambiguous and explicitly represented in the structure or format
of the data. The canonical example of structured information is a relational
database table. Unstructured information may be characterized as information
whose intended meaning is only loosely implied by its form and therefore
requires interpretation in order to approximate and extract its intended
meaning. Examples include natural language documents, speech, audio, still
images, and video."

http://www.research.ibm.com/journal/sj/433/ferrucci.html

IAW that definition, it is unstructured.  OTOH is it really 
a mixed variety and that definition, polar and incomplete?

len