BITS 0.2
( label?, ( caption )?, ( alt-text | long-desc | email | ext-link | uri )*, ( fig
| alternatives | graphic | media )* )
BITS 1.0
( ( object-id )*, label?, ( caption )?, ( abstract )*, ( kwd-group )*, ( alt-text
| long-desc | email | ext-link | uri )*, ( fig | alternatives | graphic | media )*
)
BITS 2.0
( ( object-id )*, label?, ( caption )?, ( contrib-group )*, ( abstract )*, ( kwd-group
)*, ( alt-text | long-desc | email | ext-link | uri )*, ( fig | alternatives | graphic
| media )*, ( attrib | permissions )* )
BITS 2.1
( ( object-id )*, label?, ( caption )?, ( legend )*, ( contrib-group )*, ( abstract
)*, ( kwd-group )*, ( subj-group )*, ( alt-text | long-desc | email | ext-link | uri
)*, ( fig | xref | alternatives | graphic | media )*, ( attrib | permissions )* )