This element is used in two senses:
The term <term> part of an item in a two-part (definition) list may be a term, a word, a phrase, a picture or icon, an equation, a variable, or anything else that is to be explained. The definition <def> part of an item in a two-part (definition) list need not be a “definition” in the strict dictionary sense of that word. Such a definition could be a discussion, explanation, expansion, or just a few words that tell the reader about the <term>. When a <def-list> is within a <glossary> element, the definitions are assumed to be real definitions.
<!ELEMENT def %def-model; >
... <back> ... <glossary> <def-list> <title>ABBREVIATIONS</title> <term-head>Abbreviation</term-head> <def-head>Expansion</def-head> <def-item><term id="G1">PAP I</term> <def><p>poly(A)polymerase I</p></def> </def-item> <def-item> <term id="G2">PNPase</term> <def><p>polynucleotide phosphorylase</p></def> </def-item> </def-list> </glossary> ...