Excellent primer on reading electrical control/ladder diagrams. The only thing I feel they could've made clearer were the timer contact descriptions under "Contacts" & "Contacts retarded..." they might've said instead of NOTC & NCTO timers, timing occurs when coil energizes &/or ON-Delay & for NOTO & NCTC timers, timing occurs when coil de-energizes &/or OFF-Delay. That's what all the automation electricians & control designers I worked with, including my former boss called them. I think this terminology is a little clearer because it shows what the coil's doing when timing occurs, or what initiates the timing action. Thanks Nels!