# AOM2 `EXPR_ARCHETYPE_REF` inherits `EXPR_VALUE_REF`

**Category:** [ADL](https://discourse.openehr.org/c/adl/40)
**Created:** 2025-09-15 03:25 UTC
**Views:** 30
**Replies:** 2
**URL:** https://discourse.openehr.org/t/aom2-expr-archetype-ref-inherits-expr-value-ref/11395

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## Post #1 by @Mohammad_Zawahreh

Hi,
In AOM2 I’ve noticed `EXPR_ARCHETYPE_REF` inherits `EXPR_VALUE_REF`, the link points to an invalid beom spec page(not found), so i assume it is a typo and supposed to be the [BEL](https://specifications.openehr.org/releases/LANG/development/BEL.html) page but the class is also not described there, and I looked up an old [BEOM](https://specifications.openehr.org/releases/BASE/Release-1.0.4/expression.html) page inside BASE 1.0.4 and the same problem, it is mentioned many times but no clear description about it.

the closest description I got was in EBNF grammers, is it missed from the spec or is the notion in the grammer ? eitherway should it be cleared in the text ?
`value_ref:
      function_call
    | bound_path
    | sub_path_local_variable
    | local_variable
    | constant_name
    ;`

A side note, I would be happy to help in creating a github PR to change all beom links to the BEL links in beom.

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## Post #2 by @thomas.beale

EXPR_VALUE_REF can be found in the [BEL (Basic Expression Language) spec](https://specifications.openehr.org/releases/LANG/development/BEL.html#_core_package). However, for some reason the class `EXPR_VALUE_REF` has been missed out in the spec. It can be added in very easily, and the link will work. You can [see it here in the global UML](https://specifications.openehr.org/releases/UML/development/index.html#Architecture___19_0_3_8fe028d_1652116450702_422710_5562).

This fix now has a [pull request for it here](https://github.com/openEHR/specifications-LANG/pull/1).

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## Post #3 by @Mohammad_Zawahreh

Thanks for the great work. I had opened a Jira [issue](https://openehr.atlassian.net/browse/SPECPR-468) about this earlier, so I think it can be closed now.

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**Canonical:** https://discourse.openehr.org/t/aom2-expr-archetype-ref-inherits-expr-value-ref/11395
**Original content:** https://discourse.openehr.org/t/aom2-expr-archetype-ref-inherits-expr-value-ref/11395