Scan-Move is a command available to units without an attack, such as high templar and the medivac dropship. The hotkey used is A, the same as the attack command. Using scan-move "orders selected units to move to the target area or follow the target unit. Scan-Moving units will not engage enemies."
I don't understand this description. What's the difference between scan-move and normal move? If I scan-move a high templar ... what will he do when he runs into enemies?
Also, now that I think of it - assume I have a group of units selected, where some have an attack and some don't (e.g. Zealots and High Templars). What actually happens when I hit A-click, and they run into some enemies?