What are the guidelines for placement of timing mats? I have been thinking that for a course with the same start and finish line that the mat is supposed to lie entirely behind the actual line (i.e. not on the actual course), so as to pose no risk of shortening the course simply from mat placement.
But I have seen this done different ways. Sometimes timers place those mats centered on the actual line, so that part of the mat is off the course and part is on the course.
I'd like to know what the thinking is on this question and also where to look for authoritative answers on timing questions.