Examples from "Form Optional / Required" section of the form reference: convert empty string value to {absent} with ctrl.emptyisnull=true BUT admit whitespace only using form.empty.trim=false

Field String Optional Empty Is Null(Optional)Optional string field with ctrl.emptyisnull=true can submit whitespace only value that is not converted to the {absent} (null) value because of [extra:form.empty.trim=false]. Whitespace is not collapsed.

Field String Required Empty Is Null *Required string field with ctrl.emptyisnull=true can submit whitespace only value that is not converted to the {absent} (null) value because of [extra:form.empty.trim=false]. Whitespace is not collapsed

Field String Required Empty Is Null No Html 5 *Use this no html5 version to check that empty string becomes absent - Required string field with ctrl.emptyisnull=true can submit whitespace only value that is not converted to the {absent} (null) value because of [extra:form.empty.trim=false]. Whitespace is not collapsed