I dispute the punctuation though - In Lorenzo's document examples, he uses a small perpendicular through the circle as an apostrophe (rather than the two lines below he also shows) - and he's also used a semicircle for a comma.
"This is my timey wimey detector. Goes ding when there's stuff."
Yes Sherman did invent the system. The production crew had never made the written language to begin with ( much like Klingon) so this Whovian took it upon himself to create a system that makes sense for us Earthlings to understand. I think it is brilliant, beautiful and simple enough to understand. I ( as well as many Whovians) use this form. From what I've seen it has become the standard. There are however others who have come up with their own. Anyone interested in those?