For each spacing zone within a rebar set, you can modify the length, number of spaces, and spacing value. You can also define offsets for the first and last spacing zone of a rebar set.
You can modify the spacing zone properties in the property pane or on the contextual toolbar.
On the contextual toolbar, the start offset is shown together with the first spacing zone, and the end offset with the last spacing zone. If there is only one spacing zone in a rebar set, both the start and end offsets are shown.