Examples from "Form Optional / Required" section of the form reference: convert whitespace only string value to {absent} using whiteSpace=collapse facet

Field String Optional Empty Is Null(Opzionale)Optional string field with ctrl.emptyisnull=true and whiteSpace=collapse facet, can submit whitespace only value that are converted to the {absent} (null) value. Whitespace is in any case collapsed.

Field String Required Empty Is Null *Required string field with ctrl.emptyisnull=true and whiteSpace=collapse facet, can submit whitespace only value that are converted to the {absent} (null) value. Whitespace is in any case collapsed.