Way, way back in time...
HTML is a presentational-structure markup language, with a bunch of formatting markup stuck on. All its "semantics" (as in syntax) are for presentational structure and formatting. It is not a semantic markup language, because it lacks the ability to encode "semantics" (as in meaning).
For example, HTML can express the word "bridge" in a heading, a paragraph, a blockquote etc. It cannot express whether the word "bridge" is referring to a physical structure over a gap, a card game or a denture.
To use semantic markup requires the use of a semantic markup language like the W3C's RDF, which together with OWL is the foundation of the W3C's Semantic Web [w3.org].
So I would suggest the use of the term "structured semantic markup" is wrong, or at best redundant. The most appropriate phrase to use is "structural markup" or "structured markup", and this refers to using HTML to markup presentational structure without embedding any additional formatting instructions.