I am trying to find an authority for the rules by which Western
languages are composed into lines, in particular, the rules for where
line breaks are allowed.
In some countries/languages such as France, such an authority may exist.
For most languages, it does not. Grammarians and lexicographers attempt
to discover the rules, not to invent them or prescribe them. Matters of
punctuation and typography are sometimes codified by publishing houses,
but they have no authority (though they may have influence) beyond their
own publications.
Michael Kay
XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list