Display of rend perpendicular etc

[jcowey]

When sections of text are marked with rend="perpendicular" on each line it would be good to use perhaps <note> to indicate that the following lines are written in the left / right / upper / lower margin. The line numbering would then simply be be continued without the rend="pendicular" attribute. Or would it make sense to continue it (for research purposes, collect all perpendicular lines), but not surface the information as we have done up until now.