The following diagram illustrates azimuth and elevation angles, as used by the Tool Axis page for multi-axis machining:
This shows the elevation angle, which is the angle from the Tool Axis vector's orthogonal projection onto the XY plane toward the positive Z-axis, to the Tool Axis vector. The elevation angle is between -90 and 90 degrees.
This shows the azimuth angle, which is the angle from the positive X axis toward the positive Y axis, to the Tool Axis vector's orthogonal projection onto the XY plane. The azimuth angle is between 0 and 360 degrees.