When marking poles one slash is a 30', two is a 35', 3 is a 40', on up to 55' is how we use to mark them. After that you try to write 65' or what ever the pole is. Tallest pole I've ever seen down here was a 70' back about 30 years ago. T.R. Miller in Brewton use to have a special extension trailer you could borrow to pull the over length poles.