BITS 0.2
( book-id*, subj-group*, book-title-group?, ( contrib-group | aff | aff-alternatives
| x )*, author-notes?, pub-date*, issn*, issn-l?, isbn*, publisher*, edition*, supplementary-material*,
pub-history*, permissions?, self-uri*, ( related-article | related-object )*, abstract*,
trans-abstract*, kwd-group*, funding-group*, conference*, counts?, custom-meta-group*,
( notes )* )
BITS 1.0
( book-id*, subj-group*, book-title-group?, ( contrib-group | aff | aff-alternatives
| x )*, author-notes?, pub-date*, book-volume-number?, book-volume-id*, issn*, issn-l?,
isbn*, publisher*, edition*, supplementary-material*, pub-history*, permissions?,
self-uri*, ( related-article | related-object )*, ( abstract )*, trans-abstract*,
( kwd-group )*, funding-group*, conference*, counts?, custom-meta-group*, ( notes
)* )
BITS 2.0
NO CHANGE IN CONTENT MODEL
BITS 2.1
( book-id*, ( content-version | content-version-alternatives )?, subj-group*, book-title-group?,
( contrib-group | aff | aff-alternatives | x )*, author-notes?, content-language*,
( ( pub-date )* | pub-date-not-available? ), book-volume-number?, book-volume-id*,
issn*, issn-l?, isbn*, publisher*, edition*, supplementary-material*, pub-history*,
permissions?, ( self-uri )*, ( related-article | related-object )*, ( abstract )*,
trans-abstract*, ( kwd-group )*, funding-group*, support-group*, conference*, counts?,
custom-meta-group*, ( notes )* )