VIhA (http://www.lojban.org/en/publications/reference_grammar/chapter10.html)

A tense indicating dimensionality in space (line, plane, volume, or space-time
interval).

le verba ve'a vi'a cadzu le bisli The child [medium space interval]
[2-dimensional] walks-on the ice. In a medium-sized area, the child walks on the
ice.

