On Wed, 2008-05-07 at 18:04 +0100, Thomas Beale wrote:
> this attribute is populated in memory when an archetype is deserialised,
> so it points to the actual ARCHETYPE object. In almost every case (of
> the few that there are) that there is a 'parent' reference, it works
> like this.
Okay, so now my understanding is that; the attribute contains the
parent archetype of this archetype? Not the current ("owner of this
ontology") archetype (which is circular). That kind of clears that up.
But according to the AOM spec:
"2.3.3 Archetype Specialisation
Archetypes can be specialised. The formal rules of specialisation are
described in the openEHR
Archetype Semantics document (forthcoming), but in essence are easy to
understand. Briefly, an
archetype is considered a specialisation of another archetype if it
mentions that archetype as its par-
ent, and only makes changes to its definition such that its constraints
are ?narrower? than those of the
parent. Any data created via the use of the specialised archetype is
thus conformant both to it and its
parent. This notion of specialisation corresponds to the idea of
?substitubility?, applied to data.
Every archetype has a ?specialisation depth?. Archetypes with no
specialisation parent have depth 0,
and specialised archetypes add one level to their depth for each step
down a hierarchy required to
reach them.
"
I originally read this to say that the specialization section was really
for information and not an operational requirement for an archetype
instance.
However, from your explanation. It seems to me that an archetype
instance with layers of specialization will require instances of all
parents nested within. If this is true; what value are they at
implementation?
Am I still confused? :-)
Cheers,
Tim
--
Timothy Cook, MSc
Health Informatics Research & Development Services
LinkedIn Profile:http://www.linkedin.com/in/timothywaynecook
Skype ID == timothy.cook
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