Azimuth convention for Phased Array Toolbox

I've set up 2 arrays. The antenna patterns are shown below:

From the conventions defined in https://au.mathworks.com/help/phased/ug/spherical-coordinates.html, the positive x axis is aligned with the direction of the mainlobe and azimuth is positive moving anticlockwise from this axis.

If I were to collect plane waves from some source (using phased.collectPlaneWave), I first need to define which direction the source is coming from (in az el). Is the azimuth of the source relative to the 0 deg label shown in the above antenna pattern plots, or is it relative to the direction of the mainlobes of the array?

Thanks