Warning: This may get technical
Similar to what I wrote before, I think they are referring to a stand-still in terms of *lattitude.*
Basic sphirical trig: You measure straight lines on a sphere along a great circle. If you don't know what a great circle is, it is probably worth reviewing this subject, but think of it as a circle that is formed when a sphere is bisected by a plane. All great circles divide the sphere exactly in half.
The sky is thought of as a sphere, and it appears to be such for our observational purposes.
Ok, you have four great circles to consider. The horizon, the equator, the ecliptic, and in this case the lunar orbit. The ecliptic is off from the equator by 23.25 degrees. The moon's orbit is off the ecliptic cy six degrees, iirc. Each of these circles cross eachother at two points:
The ecliptic crosses the equator at 0Ari and 0Lib. The moon crosses the ecliptic at the two nodes. The horizon crosses the ecliptic at the ascendant and descendant, and crosses the equator in such a way that a given point on the horizon will always correspond to a given celestial lattitude.
Understandable so far?
Normally, one will see the moon rise at different points on the horizon every day as it travels along its orbit which is fairly close to the ecliptic. As the moon moves north, it will rise further to the north. As it moves south, it will rise further to the south. These cycles are not exactly in phase, and the moon's nodes slowly move retrograde. What this means is that over time, the way in which the moon's apparent N/S motion (vs. the ecliptic) combines with the Ecliptic's skew vs. the equator. At certain points, the Moon's orbit may be skewed to the ecliptic such that it is parallel to the equator for a short time.
A couple points:
1) This happens twice a lunar cycle. Yes, it happens twice *every* lunar cycle.
2) Some times may see a lunar cycle that is closer to the equator than others. So this effect may *seem* more pronounced.
The bigger question is what is gained by looking at equatorial nodes and "lunastace" points rather than ecliptical nodes?