Spacebands are also called "bands in space" or "BiS".
A spaceband tends to pull its starting segment toward the point in space during wiggle and other operations.
A very short spaceband tends to keep the starting segment at the same spot.
Recipes can draw spacebands using precise geometry.
The length attribute of a space band is always zero. On a segment-to-segment band, the length attribute gives you the current distance between the endpoints of the band. A spaceband does have a goal length, which can be set and queried like the goal length of a segment-to-segment band.