null value of Element

Technical (archive)
1

Hi,

I have an archetype with following Element

ELEMENT[at0033] occurrences matches {0..1} matches { -- Condition Status
    value matches {
       DV_TEXT matches {*}
    }
}

I noticed that it is not possible te create an Element-instance with
data-value null, because my own Object-validator validates against this
archetype and complains that in this case, value is a required attribute.

Now I wonder, is that so? Maybe I should change my object-validator?

Is it so that in an archetype-snippet like this, value is a required
attribute? Or is it also possible to use the nullFlavor-attribute
instead, in that case I need to change my Object Validator

Thanks for any advise

Bert

2

Bert Verhees wrote:

ELEMENT[at0033] occurrences matches {0..1} matches { -- Condition
Status
   value matches {
      DV_TEXT matches {*}
   }
}
...

Is it so that in an archetype-snippet like this, value is a required
attribute?

According to the openEHR data structures specification, ELEMENT.value
is 0..1. It's optional, as long as a null flavour is supplied.

Invariants:
Is_null_valid: is_null = (value = Void)
Null_flavour_indicated: is_null xor null_flavour = Void

In other words, (value = Void) = not (null_flavour = Void). The
ELEMENT must have either a value, or a null flavour, but not both.

- Peter Gummer