Hi Bert,
existence is a property of CAttribute (multiple or single). It indicates
if the attribute value (i.e. some object) must exists or can be null.
occurrences is a property of a CObject, and indicates how many instances
of that object constraint can exist in the data.
It can be used on CObjects under CMultipleAttributes to indicate how
many instances of each CObject (there can be multiple CObjects, e.g.
systolic bp, diastolic bp etc, each of which could potentially have more
than one instance in the data). Commonly, many objects under a
CMultipleAttribute can only have one or zero occurrences, so occurrences
is set to {0..1}
Occurrences on an object under a CSingleAttribute can only indicate 0..0
or 1..1 (based on an original value of 0..1). In theory, occurrences on
an object under a CSingleAttribute could conflict with existence on the
CSingleAttribute. Tools can easily check this (and they do).
hope this helps.
- thomas
On 06/01/2013 15:51, Bert Verhees wrote:
> Excuse me the following question, maybe I am just looking over the
> answer all the time
>
> What is the use of both together existence and occurences in case of a
> CSingleAtttribute.
>
> And what if both have conflicting information?
>
> For example, existence gives REQUIRED and occurrences gives minOccurs=0
>
> Thanks for a short answer
