These are various keyboard shortcut commands tied to assisting the player when it comes to building structures or units with engineers and factories respectively in Supreme Commander.

Left Click on unit picture: Build 1 unit/structure
Shift + Left Click: Build 5 units
Right Click: Cancel building 1 unit/structure
Shift + Right Click: Cancel building 5 units/structures

Left Click on the map and hold: Build structures in this line
Shift + Ctrl + Right Click on a structure outline: Cancel building this structure

B: Toggle Build Mode
     * In Build Mode, keyboard shortcuts refer to each individual building.
     * For more about Build Mode, see later sections of this guide.

Esc: Exit Build Mode