Sentence:  In preparation for laying out the <WSD>easement</WSD> used to join the first- and second-flight handrails, tack a piece of plywood about 5 inches wide to the bottom side of the gooseneck fitting and the handrail of the first flight. These pieces are used to rest the connecting <WSD>easement</WSD> against when laying out the joint. 
Meaning of the word marked with <WSD> tags:  An element such as a baseboard, handrail, etc., that is curved instead of abruptly changing direction.