This "OL_DOC.DH" tag is used to define the start of an ordered list. The list ends when the "<$eOrdListCompact>" tag is encountered. Lists can be nested.
Each list item begins with <$li>. List items are not separated by a blank line, if you want one then use the "<$OrdList>" tags instead.
<$OrdListCompact>
<$li>Item1
<$li>Item2
<$eOrdListCompact>
For an example have a look at the Lists documentation.