Stop SCV from building without cancelling

Question

In pro-level games, I often see Terran players pulling SCVs off half-completed buildings without cancelling the buildings (shown here). How do you do that?

Answer 1

What you are referring to is the SCV Halt command (hot key T). By issuing this command you can regain control of your scv and issue a movement command (moving it to safety) without canceling the building. Another SCV can then be right clicked onto the building to finish it.