These commands on the Edit menu apply to sections and parts within sections. If the current section contains only one part, the Rotate-Part command is the same as the Rotate-Section command, and the Mirror-Part command is the same as the Mirror-Section command.
The Rotate command rotates the current part or entire section about the origin. A positive angle rotates counter-clockwise. If any computations have been performed prior to rotating a section, the default rotation angle is the negative of the angle of the major axis (a). Alternatively, you may choose Principal Axes from the Rotate menu.
The Mirror command mirrors the current part or entire section. The mirror angle you specify defines a line through the origin about which the part or section is flipped. For example, a 90 degree mirror angle flips left and right, and a 0 degree mirror angle flips top and bottom.
If the rotate or mirror transformation is orthogonal, the placement references to the edges of parts will be adjusted accordingly. Otherwise, the placement references will be set to the center of gravity.