This is a reference for the CAD terms used in this guide
A Feature is a term used to refer to objects or entities created by the CAD system such as a hole chamfer round or extrude etc.
Linear symmetry;- A part is considered to have linear symmetry when the geometric shape of that object is identical on opposite sides of a dividing line or central axis.
Parametric constraints allows links to be created across a series of parts or features. These links generate associations between parts and ensure that changes made to the a part update any other parts. For example, when a hole size changes, the diameter of the bolt that fits that hole, automatically updates.
Rotational symmetry; - A part is considered to have rotational symmetry when any given cross section of that part is rotated around an axis by an angle of 360°/n (or 180°, 120°, 90°, etc.) the shape does not alter.