I orderd the book. It contains exactly what wbd says. However, there was nothing new or earth shattering in it. It is a compilation of information I already have in one place versus across several sources.
If that is worth $25 plus shipping, get it. It was not worth it for me.
Just one...
Is this too simple-minded or could you attach some sort of identification onto the cable similar to what is used in substations when marking control wires?
If not, perhaps a tie-wrap and some paper in a laminated covering...
This one is good, too. It is published by the RUS (which used to be the Rural Electrification Administration)
It goes into much more than just sag.
http://www.usda.gov/rus/regs/bulls/160-2.pdf