Returns a ParagraphFormatting.LineSpacingRule object that represents the type of line spacing for a paragraph. There are 3 types: AtLeast, Exactly, and Multiple. AtLeast and Exactly use twips to specify a minimum height and exact height respectively. One twip = (1/20 pt) or (1/1440 in). Multiple specifies a spacing as a number of lines. Multiple is the most common type of spacing.