Thanks, guys,
I'll make a template just for diagrams.
And thanks, Dave for reminding me of the 'warehouse.' I didn't plan on using symbols, but rather pictures of the actual items (in some cases) and 2D drawings of the items in others. In other words a diagram anyone can follow. Light on words and heavy on graphics.
So a follow-up question would be, can one create a private 'library' of related stuff? Searching the warehouse can get tedious.
One that comes immediately to mind would be a library of construction lumber. I have to rebuild my deck next summer and I wanted to try a different design. It would so cool to grab a 2 x 6, (or other dimensioned lumber) copy it, cut it as necessary, and paste it into place, as an example. That also helps my thought process and reveals a process to follow in the building. For me that means cutting far fewer pieces to the wrong size!