Field can only be used in topic headings
Help Producer checks the syntax for every field in the help document. If a Help Producer field is found that must be placed inside a topic heading, the warning message ‘Field can only be used in topic headings’ will be displayed.
To fix this error, press ALT+F9 to display hidden fields and move the field inside the topic heading. For details on the syntax of Help Producer fields, see the topic Help Producer Fields.