The following markup puts "structural elements" in a special font (boldface with a dotted underscore) to indicate it is a glossary term and creates a hyperlink to the glossary. Because the glossary entry contains a space, the text is in quotes. The plural form appears in the text. HelpTag checks for the singular form in the glossary and reports an error if it is not found.
SGML views a document as a hierarchy of <term "structural element"|structural elements|.