This function is used to find the index of a source string in a field or named variable. A specified track or named variable is set to the zero based index or -1 if the source string is not contained. Note that an empty source string always sets the variable to -1. The search can be performed case insensitive and/or diacritical mark insensitive.
The action test state will be set to true if the source string was found, otherwise false.
The source string and the optional named variable fields may contain any of the escape sequences described in Escape Sequences.
The function is intended primarily for grouped execution mode. In stepwise execution mode, the operation is only performed once on the first selected file.
See the Unicode Strings topic for additional information which effect the usage of this statement.