Ruler tool is used to measure the following magnitudes defined between two points:

DistanceProjected distance on a horizontal plane. XY Distance
Azimuth Angle between line defined by the two point and the north
ElevationAngle formed by the difference elevation
P1 MSLAltitude of Point 1 with respect to sea level
P2 MSLAltitude of Point 2 with respect to sea level
DifferenceDifference of altitude

Ruler – Magnitudes

fig.164-mission-ruler-exampleRuler Example