O L Leigh:1123611 said:I'm sure it's an acronym, although I don't know what it stands for. The name relates to the software package that generates the print-outs.
But it's not the diagrams themselves that are called Sheilas, it's the schedule cards with the timings and stopping patterns on them.
O L Leigh
Here's an example of a guard's schedule, they look the same for a driver.