How far (degrees, in the plane) the plane's ascending node on the ICRF
EQUATOR sits from its node on the reference (ecliptic) plane — add this
to a node longitude published from the equatorial origin (as JPL's
planetary-satellite mean elements are: "measured from the node of the
reference plane on the ICRF equator") to get it from the origin this
engine uses (planeBasis's x-axis).
How far (degrees, in the plane) the plane's ascending node on the ICRF EQUATOR sits from its node on the reference (ecliptic) plane — add this to a node longitude published from the equatorial origin (as JPL's planetary-satellite mean elements are: "measured from the node of the reference plane on the ICRF equator") to get it from the origin this engine uses (planeBasis's x-axis).