Changes

<texcode>

\definepagebreak[chapter][yes,footer,right]

'''Bookchapters'''. Red chapter number, set off from title text by a vertical bar. Chapters always start on a right (odd) page. If the even page preceding it is empty, there should be no page number. I tried "before={\ifodd\realpageno\else\page[empty]\fi}" which works if "page=yes"; but it messed up other things, so I ended up by removing page numbers manually in "Acrobat".