>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.

What do you mean by authority, hopefully not something on the order of
ISO?

Do you mean something like this:
http://www.bartleby.com/141/strunk.html#8

Although perhaps a philologically oriented rule, as in the tradition of
line breakage was established....?


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