Hi Ian, in my opinion an empty string has a semantic difference with a null value. Empty string is however a valid value. For example, I could have different cases for "Comment" in openEHR-EHR-OBSERVATION.blood_pressure.v1: - a non-empty string with the comment on blood pressure measurement. - an empty string, meaning that no comment has been given from the doctor, because not needed (doctor judges that no comment is necessary) - a null value, meaning that no comment has been asked to the doctor, because exluded from the template/GUI. Or there are an other way to model these three cases?
Regards, leo Ian McNicoll-3 wrote: > > Hi Leo, > > An important principle under-pinning openEHR is that 'empty' data is not > normally recorded, which is consistent with general clinical practice > information recording. > > On this basis, I am not sure I can see the use case for recording "" i.e. > Empty text. If a text data entry field is left blank, this would simply > not > be recorded in openEHR data. If the field is mandatory, either the user is > forced to make some sort of entry or perhaps is allowed to select one of > the > null values as you suggest. > > Regards, > > Ian > > Dr Ian McNicoll > office / fax +44(0)141 560 4657 > mobile +44 (0)775 209 7859 > skype ianmcnicoll > ian.mcnicoll at oceaninformatics.com > ian at mcmi.co.uk > > Clinical Analyst Ocean Informatics openEHR Archetype Editorial Group > Member BCS Primary Health Care SG Group www.phcsg.org / BCS Health > Scotland > > > > On 25 June 2010 16:07, Moretti Leonardo <lmoretti at noemalife.com> wrote: > >> 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 >> >> _______________________________________________ >> openEHR-technical mailing list >> openEHR-technical at openehr.org >> http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-technical >> > > _______________________________________________ > openEHR-technical mailing list > openEHR-technical at openehr.org > http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-technical > > -- View this message in context: http://old.nabble.com/Empty-string-for-DV_TEXT-tp28993527p29022604.html Sent from the openehr-technical mailing list archive at Nabble.com.
