> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/observable-entity/observable-entity-modeling.md).

# Observable Entity Modeling

<mark style="color:$danger;">**This Editorial Guide is used for Education Purposes Only. It is used in the Authoring Courses and Certifications. It is based on the January 2026 Editorial Guide.**</mark>

## Observable Entity Modeling

When observable entity concepts have been given a value, they behave like clinical findings, with respect to the *concept model* for context.

When observable entity concepts have *not* been given a value, they behave like procedures, with respect to the *concept* *model* for context.

## Modeling

The observable entity model has been implemented in limited content areas in SNOMED CT thus far. Most of the content in the hierarchy is primitive.

* Over 165 observable entity concepts have been modeled describing physiological measurements (body temperature, respiratory rate, heart rate, blood pressure). Most of these are sufficiently defined using the attributes. |Vital sign (observable entity)| has been inactivated since it could not be universally defined.
* Additional concepts using observable entity attributes have been defined since the January 2020 release. The majority of the changes are related to nutritional intake (e.g., food intake, vitamin intake, fasting pattern) observable entity concepts.

Susceptibility observables should be modeled in accordance with the specified templates.

## Topics in this section

{% content-ref url="/pages/Q5nEAWJlbuj26sFUj2o2" %}
[Body temperature](/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/observable-entity/observable-entity-modeling/body-temperature.md)
{% endcontent-ref %}

{% content-ref url="/pages/MEKLWzezunfa1jsoopkl" %}
[Mass vs Weight](/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/observable-entity/observable-entity-modeling/mass-vs-weight.md)
{% endcontent-ref %}

{% content-ref url="/pages/LZQT4JcqQV8qIPlSm6eA" %}
[Neoplasm Observables](/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/observable-entity/observable-entity-modeling/neoplasm-observables.md)
{% endcontent-ref %}

{% content-ref url="/pages/v3aV9AsnHaqJuDQ3DWKB" %}
[Nutritional intake observable entities](/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/observable-entity/observable-entity-modeling/nutritional-intake-observable-entities.md)
{% endcontent-ref %}

{% content-ref url="/pages/Qz5m297DHNNAXKdPd95O" %}
[Observable Entity and Microbiology Test Results](/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/observable-entity/observable-entity-modeling/observable-entity-and-microbiology-test-results.md)
{% endcontent-ref %}

{% content-ref url="/pages/84uWpIu5TYes0PnbepOp" %}
[Observable Entity Templates](/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/observable-entity/observable-entity-modeling/observable-entity-templates.md)
{% endcontent-ref %}

{% content-ref url="/pages/jaqVT8OMfIEardmOA8vD" %}
[Relationship between Observable Entities and NPU codes](/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/observable-entity/observable-entity-modeling/relationship-between-observable-entities-and-npu-codes.md)
{% endcontent-ref %}

{% content-ref url="/pages/wL3PGlXN6yFcexomjMib" %}
[Representing LOINC Terms with the SNOMED CT Observable Entity Model](/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/observable-entity/observable-entity-modeling/representing-loinc-terms-with-the-snomed-ct-observable-entity-model.md)
{% endcontent-ref %}

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