In http://www.openehr.org/releases/1.0.2/architecture/rm/data_types_im.pdf, DV_TEXT is defined as a text item. Among "Invariants" (page 29), I found that this data type is valid if it is not empty (Value_valid: value /= void and then not value.is_empty and then not(value.has(CR) or value.has(LF))).
Does this mean empty string is not a valid value for DV_TEXT? If so, why empty string cannot be a valid value? An empty string could be meaningful, with a different semantic than null value! Many textual information could be an empty string (comments, descritpions..). An empty string means that the value is exactly a void string, a null value means that the information is unknown, not taken, not asked! Regards leo
