# EHR specification

**Category:** [Technical (archive)](https://discourse.openehr.org/c/technical-archive/156)
**Created:** 2006-11-20 12:30 UTC
**Views:** 5
**Replies:** 2
**URL:** https://discourse.openehr.org/t/ehr-specification/14595

---

## Post #1 by @Mattias_Forss1

Hi all,

I found there is an error at page 42 in the class description of CONTENT_ITEM in the EHR specification. As you can see in the inherit field, the class inherits itself, but it should inherit the class LOCATABLE from the common package instead.

Another thing I would like to be clarified is that the archetype_details field of LOCATABLE is mandatory for all archetype root points. The COMPOSITION and ENTRY classes have the following invariants respectively:

Is_archetype_root: is_archetype_root
Archetype_root_point: is_archetype_root

However, it should probably be pointed out that if either of the classes are archetype root points, the archetype_details field inherited from LOCATABLE is mandatory and must not be void. I assumed that COMPOSITON classes can be archetype root points as well, but I am not sure of the meaning of the term.

Regards,

Mattias

---

## Post #2 by @thomas.beale

Mattias Forss wrote:
> Hi all,
>
> I found there is an error at page 42 in the class description of
> CONTENT\_ITEM in the EHR specification\. As you can see in the inherit
> field, the class inherits itself, but it should inherit the class
> LOCATABLE from the common package instead\.
>

fixed \- thanks
> Another thing I would like to be clarified is that the
> archetype\_details field of LOCATABLE is mandatory for all archetype
> root points\. The COMPOSITION and ENTRY classes have the following
> invariants respectively:
>
> Is\_archetype\_root: is\_archetype\_root
> Archetype\_root\_point: is\_archetype\_root
>
> However, it should probably be pointed out that if either of the
> classes are archetype root points, the archetype\_details field
> inherited from LOCATABLE is mandatory and must not be void\. I assumed
> that COMPOSITON classes can be archetype root points as well, but I am
> not sure of the meaning of the term\.

See the class LOCATABLE \- you will see it has the invariant:

Archetyped\_valid: is\_archetype\_root xor archetype\_details = Void

this means that if is\_archetype\_root is True, then archetype\_details /= Void

\- thomas

---

## Post #3 by @Mattias_Forss1

2006/11/22, Thomas Beale <[Thomas.Beale@oceaninformatics.biz](mailto:Thomas.Beale@oceaninformatics.biz)>:

> See the class LOCATABLE - you will see it has the invariant:
>
> Archetyped_valid: is_archetype_root xor archetype_details = Void
>
> this means that if is_archetype_root is True, then archetype_details /= Void

Ah, it says 'xor' and not 'or' :-)

Thanks,

Mattias

---


**Canonical:** https://discourse.openehr.org/t/ehr-specification/14595
**Original content:** https://discourse.openehr.org/t/ehr-specification/14595