Wmodavis, to try to add to FB's description try this.

If you strip open some brake housing you'll find that there is small, flat steel banding that is wound tight like a closed exansion spring. With that style when you bend it into a curve the outer spiral wraps will open a little but the spiral steel wrapping maintains contact on the inside of the curve. You can see this if you have a small but long exapansion spring that is totally collapsed and coil bound when at rest and bend it into a curve. The windings open up on the outside but stay in tight contact on the inside. This would be the low helix angle. Or another way to describe it would be tight wound or coil bound winding.

Now if you strip open some shifter housing instead of this spiral wrapping you'll find a bunch of pretty much lengthwise wires that twist around the inner core only about 1/5 to 2 turns over a foot of length foot. I'm a bit foggy on the number because I've never stripped any back far enough to count the turns but from what I've seen it seems about right. This would be a high helix angle of only a few degrees inclination from axial.

From actual use Shimano found that brake style housing did not have quite enough resistance to compressing as they needed for SIS shifting. Hence the development of the stiffer "compressionless" shifter housing that we all use these days.