The conditional processing property of the spatial index rules is used to support conditional processing of an index on a document by document basis.

If not present, the index is processed for every document identified by the package, horizontal data field and vertical data field defined by the rule.

If present, the field must contain a numeric literal or literal expression that can be evaluated. ( See the Flexible Search Programming Language documentation. ) If the expression evaluates to zero ( 0 ) no processing takes place. If, however, the expression evaluates to anything other than zero ( 0 ) the index is processed for that document.

When referencing field data from within the expression, use the construct "dollar-underscore-field_ID-dollar" i.e. =$_1$ would reference the first field in the data field list.