Alternatively, after defining or searching for the gaps, you can click
Heal >
Close without adding the gaps to the wireframes. If you use
Heal >
Close without adding the defined gaps to the wireframes, you can close gaps between any surfaces, even gaps that do not belong to the same base nodes.
Heal >
Close adds the gaps to the wireframes and converts the wireframes to satisfied wireframes. However, you cannot define gaps between surfaces that belong to the merge nodes.