What is the Cartesian sign convention used for spherical mirrors ?

Explanation

According to the Cartesian sign convention, the pole (P) of a spherical mirror is taken as the origin and the principal axis is taken as X-axis of the coordinate system.
(1) The object is always placed on the left of the mirror.
(2) All distances parallel to the principal axis are measured from the pole of the mirror .
(3) All distances measured to the right of the origin (pole) are taken as positive while distances measured to the left of the origin (pole) are taken as negative.
(4) Distances mearued perpendicular to and above the principal axis are taken as positive .
(5) Distances measured perpendicular to and below the principal axis are taken as negative .
(6) The focal length of a convex mirror is positive while that of a concave mirror is negative.