- Subsystems: the collection with the basic hardwares, along with the basic functions that controls them.
- Coordinators: higher level abstractions of multiple subsystem, carrying out a coordinated behavior.
- Commands: something that calls a function defined in the subsystems.
- Use METER as the unit of length. NO INCHES, FEETS AND YARDS. NO CENTIMETERS AND MILIMETERS. Transition will be stated explicitly.
- Use DERGREE as the unit of angle. NO RADIANS.
- Take CLOCKWISE (abbreviated as CW) as the positive direction of rotation. NO CONTER-CLOCKWISE (abbreviated as CCW) unless stated explicitly.