DocBook Index: more than three levels needed

Greetings!

 

We are 
beginning to use DocBook to mark up codes of ordinances, and it is serving 
quite well! The books we publish, however, include in-depth 
indexes, with up to six levels of entries. Here is an example of an index entry 
from one of our publications:

 

ALCOHOLIC 
BEVERAGES

=Fines, forfeitures and other penalties

==Excise taxes

===Collection

====Refund of tax, penalty or interest paid more than once or 
illegally collected 
..... §6-156

 

As far as we can see, the 
levels provided in DocBook (<primary>, <secondary> and 
<tertiary>) are not going to be in-depth enough to accommodate this level 
of indexing. 

 

This is what the mark-up 
might look like, but we need suggestions on how to handle the entries AFTER the 
tertiary level:

 

<section>

    
<title>Sec. 6-156. Refund of tax, penalty or interest paid more than once 
or illegally collected</title>

...

<indexterm>

<primary>ALCOHOLIC 
BEVERAGES</primary>

<secondary>Fines, forfeitures 
and other penalties</secondary>

<tertiary>Excise 
taxes</tertiary>

<what 
here?>Collection</what 
here?>

<what 
here?>Refund of tax, penalty or interest paid more than once or 
illegally collected</what 
here?>

<indexterm>

...

</section>

 

We are hoping for advice from 
anyone who may have already encountered this issue, or thoughts about how we 
might handle it.

 

(Note that our product of 
primary concern is the printed version, and for this, we have XyEnterprise's XML 
Professional Publisher v7.2c.1, which can "extract" and print up to nine 
levels of index entries...that is, once we define the nine levels in 
mark-up for it to consume.)

 

Gratefully,

LaRae Chasteen
Municipal Code 
Corporation