State the sign convention used to measure distances from a mirror.

(N/A) According to the New Cartesian Sign Convention for spherical mirrors:
$1$. The object is always placed to the left of the mirror,so light travels from left to right.
$2$. All distances parallel to the principal axis are measured from the pole $(P)$ of the mirror.
$3$. Distances measured in the direction of incident light are taken as positive $(+)$.
$4$. Distances measured opposite to the direction of incident light are taken as negative $(-)$.
$5$. Distances measured perpendicular to and above the principal axis are taken as positive $(+)$.
$6$. Distances measured perpendicular to and below the principal axis are taken as negative $(-)$.