I forget what the proper terminology is for when we talk about slack and how it can be loose or more taut but for now I will just say pull out the slack to mean more taut.
Normally when I do my standing it's been the areas between my feet up to the bottom of the back of the ribs where I can do things to stand tall and pull out the slack. More recently I've been feeling like the stuff under the ribs is an area where I can stand taller and try to pull out the slack. The other day I was working on this (pulling out the slack in the rib area along with the feet/knee/legs/perenium area/back area below the ribs) and I started to get this feeling in one of my legs between the ankle and knee, it felt like a stretch but it felt like a different kind of stretch. When I went from doing the foot couple to working on the transverse couple, the sensation of stretch in the foot couple felt the same or similar to the stretch in the back pelvis area. I'm not sure if this newer feeling was just a one time thing or I'm wondering if when we start to access the deeper layers to the stretches have a different quality to them, or should the stretches in the different parts of the body feel the same but just in different places.
Also, maybe this is unrelated, I did feel like when I was doing the rib stuff it my shoulders/arms were lowering/rotating downwards but it all felt pretty gentle and natural. Today I am feeling quiet sore in the shoulder areas, not sure if feeling more in/under the ribs is related to shoulders at all or if this would be related to other physical activity.