Within the 'list' tag add an 'item' tag. So the breadcrumb trail would be
item>lists>item(s). Each 'item' tag wraps around each index entry (it’s content
is the index term).
Step 3: Add a <ref> tag to the items in the list.
The 'ref' tag has a target attribute, its value is a space separated list of
paragraph XML IDs. The 'ref' tag references the paragraphs in the body text.
Begin to add your index terms between the item/ref tags.
Add the XML ids (from the paragraph(s) or other tags) in the target attribute
of the <ref> tag. If there are multiple XML ids related to the index term,
separate these with a space.