%sec-opt-title-model; Content Model for an Untitled Section

The model for a section-like structure that may or may not have an initial title.
Declaration
<!ENTITY % sec-opt-title-model
                        "(title?, (%para-level;)*, (%sec-level;)* )" >
Expanded Declaration

(title?, (answer | answer-set | boxed-text | chem-struct-wrap | code | explanation | fig | graphic | media | preformat | question | question-wrap | question-wrap-group | supplementary-material | table-wrap | disp-formula | disp-formula-group | def-list | list | p | disp-quote | speech | statement | verse-group)*, (sec)* )