You hit the nail on the head Doug. Back in the late 1980's, a few of my college instructors spent way to much time trying to explain just this topic. Reading this thread, reminded me of the discussions in class. I picked up on it right off, enough to pass class Q&A and written tests.
It was very close to what I had been doing for years at work, investigation and evidence collection, and the dreaded documentation of it all. (What is it? Where was it found? Where is it now? Chain of custody stuff, etc.) Days, Weeks, Months, & Years later, could someone pick up your documentation, and know what your talking about, retrace your steps, and track down all the evidence.
Several years later, in the late 1990's ... I was sitting in a college classroom, the class was a new one, not AJ, not Law, not History. It fit between the cracks of them all ... it was Genealogy. The instructor had two requirements, so as not to waste any class time, by the next class you had to have in your hands and have read it ... Evidence! by Elizabeth Shown Mills.