Model

<!ENTITY % question-model
                        "((%id.class;)*, sec-meta?,
                         label?, title?, subtitle*, alt-title*,
                         ( (%sec-level;)+ |
                           ( (%para-level;)+, (%sec-level;)* ) ),
                         (%option.class;)*,
                         (%sec-back-matter-mix;)* )"                 >

Expanded Model

((object-id)*, sec-meta?, label?, title?, subtitle*, alt-title*, ( (sec)+ | ( (address | alternatives | answer | answer-set | array | block-alternatives | boxed-text | chem-struct-wrap | code | explanation | fig | fig-group | graphic | media | preformat | question | question-wrap | question-wrap-group | supplementary-material | table-wrap | table-wrap-group | disp-formula | disp-formula-group | def-list | list | tex-math | mml:math | p | related-article | related-object | disp-quote | speech | statement | verse-group)+, (sec)* ) ), (option)*, (fn-group | glossary | ref-list)* )