level, actual, and encap).
In the latter mode, there is a collection of entries that may be represented
as a long list for an entire document, or as a short list for a section.
Each key-pattern pair in the list is processed as in the former case.
Provisions are also available to help construct the list.
With such powerful mechanisms available, there is a tendency to ``over index'' because it is so easy to be comprehensive. In some cases, ``less may be more''. Therefore, one should be extremely careful in confirming the insertion of key to avoid false drops picked up by the search mechanism.