A Multi-Line-String is a collection of zero or more geometry or geography LineString instances. Figure 1 shows examples of line-string geometries.

(1) is a simple Multi-Line-String instance whose boundary is the four end points of its two LineString elements. (2) is a simple Multi-Line-String instance because only the end points of the LineString elements intersect. The boundary is the two non-overlapping end points. (3) is a non-simple Multi-Line-String instance because the interior of one of its LineString elements is intersected. The boundary of this Multi-Line-String instance is the four end points.(4) is a non-simple, non-closed Multi-Line-String instance.(5) is a simple, non-closed Multi-Line-String. It is not closed because its Line-Strings elements are not closed. It is simple because none of the interiors of any of the Line-Strings instances intersect.(6) is a simple, closed Multi-Line-String instance. It is closed because all its elements are closed. It is simple because none of its elements intersect at the interiors.

Figure 1: Examples of multi line string geometries