index.on.type boolean
index.on.type Select indexterms based on type attribute value

## Description

If non-zero, then an index element that has a type attribute value will contain only those indexterm elements with a matching type attribute value. If an index has no type attribute or it is blank, then the index will contain all indexterms in the current scope.

If `index.on.type` is zero, then the type attribute has no effect on selecting indexterms for an index.

For those using DocBook version 4.2 or earlier, the type attribute is not available for index terms. However, you can achieve the same effect by using the role attribute in the same manner on indexterm and index, and setting the stylesheet parameter index.on.role to a nonzero value.