The prime uses phrases like "open sentence"...

[Tim Wessman]

Basically, how does one describe the form of '<something>=<something>' when NEARLY ALL users because confused regarding the use of "equation" when they saw the adv graphing symb screen?

Users are just so used to seeing the y= form that they couldn't associate any other form of entry for a graphing screen. There had to be some way to indicate that "this is not a normal graphing entry item" that distinguished it from the "normal equation" for drawing a graph. We tried several things, and that was the one that was most understood by testers and worked better then anything else.