Okay - I have not been able to verify any other rules than those few that Braille Formats mentions:
BF 1.7.2 Double-spacing is often requested when a reader is learning braille.
a.Use two blank lines wherever there is normally one blank line.
b.Insert a blank line before and after a page change indicator.
Exceptions:
g.Do not insert any blank lines after a top box line.
h.Do not insert any blank lines before a bottom box line.
I hope this helps!
Cindi