# Validate Concept Definitions and Expressions

## Overview

#### Concept Definitions

A concept definition is a set of one or more axioms that partially or sufficiently specify the meaning of a SNOMED CT concept.

## **Concept Definition Validation Requirements**

Concept definitions must conform to the SNOMED CT Concept Model as specified by the machine readable concept model. A concept with a definition that does not conform to the concept model cannot be accurately classified.

## **Service Requirements for Concept Definition Validation**

* Terminology services supporting SNOMED CT authoring **must** validate concept definitions based on concept model rules.
* Services only for terminology use **do not** need to meet this requirement.

### SNOMED CT Expressions

An expression is a structured combination of one or more concept identifiers that represents an idea.

**Example**

{% code overflow="wrap" %}

```
284196006:363698007=770850006
```

{% endcode %}

**Example (with terms)**

{% code overflow="wrap" %}

```
284196006 |burn of skin| : 363698007 |finding site| = 770850006 |Skin structure of left index finger|
```

{% endcode %}

### **Expression Validation Requirements**

Expressions should conform to the SNOMED CT Concept Model and be classifiable by a [description logic classifier](https://confluence.ihtsdotools.org/display/WIPGLOSS/description+logic+classifier).

**Transforming Invalid Expressions to Valid Expressions**

* Move refining attributes into valid groups.
* Nest refinements where required.
* Move context attributes into a context wrapper.

**Example Transformation (Laterality applied to body structure):** Invalid:

{% code overflow="wrap" %}

```
71620000 |fracture of femur| : 272741003 |laterality| = 7771000 |left|
```

{% endcode %}

Valid:

{% code title="" %}

```
=== 7523003 |Injury of thigh| +
    46866001 |Fracture of lower limb| :
        { 363698007 |Finding site| = ( 71341001 |Bone structure of femur| :
            272741003 |laterality| = 7771000 |left| ),
          116676008 |Associated morphology| = 72704001 |Fracture| }
```

{% endcode %}

**Service Requirements for Expression Validation**

Services supporting use of [postcoordinated expressions](https://confluence.ihtsdotools.org/display/WIPGLOSS/postcoordinated+expression) should support expression validation.

## Requirements and Options

Services Required

| Service Name and Status                                                                                       | Input                                                                                                                                                                                                                                               | Response                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| ------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| <p><strong>Validate expression</strong></p><p><strong>RECOMMENDED</strong><br></p>                            | <ul><li>Edition and Version</li><li>Expression to be validated</li><li>Optional: Language/dialect<a href="https://confluence.ihtsdotools.org/display/DOCTSG/4.14+Validate+Concept+Definitions+and+Expressions#footnotes"><sup>1</sup></a></li></ul> | <ul><li>Indication of whether the expression is valid or invalid</li><li><p>If the expression is invalid an indication of the reason for failure of validation<br></p><ul><li><p>Syntax error including:</p><ul><li>Character position of first syntax error, and/or</li><li>More specific error message(s).</li></ul></li><li><p>Concept model validation error including:</p><ul><li>Character position of start of invalid element and/or</li><li>Reference to failed concept model rule(s).</li></ul></li><li><p>Terming errors including:</p><ul><li>Indication of any terms in the expression that do not match valid descriptions for the identified concept.</li></ul></li></ul></li></ul> |
| <p><strong>Transform invalid expression</strong></p><p><strong>OPTIONAL</strong><br></p>                      | <ul><li>Edition and Version</li><li>Invalid candidate expression for adjustment</li></ul>                                                                                                                                                           | <ul><li>Structurally adjusted valid expression</li><li>An error message if it is not possible to transform to valid expression</li></ul>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| <p><strong>Validate concept definition(s)</strong></p><p><strong>ONLY REQUIRED FOR AUTHORING</strong><br></p> | <ul><li>Edition and Version</li><li>Identifier(s) of concept(s) to be validated</li></ul>                                                                                                                                                           | <ul><li><p>Indication of validation results for one or more concepts including</p><ul><li>Nature of error</li><li>If appropriate a reference to a failed concept model rule</li></ul></li></ul>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |

### Interdependencies

#### Required By

* [3.2.3 EHR Data Entry](https://confluence.ihtsdotools.org/display/WIPTSG/3.2.3+EHR+Data+Entry)
* [3.2.2 EHR Data Entry Design](https://confluence.ihtsdotools.org/display/WIPTSG/3.2.2+EHR+Data+Entry+Design)
* [3.8 Support Terminology Authoring and Review](https://confluence.ihtsdotools.org/display/WIPTSG/3.8+Support+Terminology+Authoring+and+Review)

#### Depends On

* [4.1 Select Edition and Version](https://confluence.ihtsdotools.org/display/WIPTSG/4.1+Select+Edition+and+Version)
* [4.2 Get a Concept, Description or Relationship](https://confluence.ihtsdotools.org/display/WIPTSG/4.2+Get+a+Concept%2C+Description+or+Relationship)
* [4.3 Get Terms for a Concept](https://confluence.ihtsdotools.org/display/WIPTSG/4.3+Get+Terms+for+a+Concept)
* [4.4 Get Definition of a Concept](https://confluence.ihtsdotools.org/display/WIPTSG/4.4+Get+Definition+of+a+Concept)
* [4.5 Get and Test Concept Subtypes and Supertypes](https://confluence.ihtsdotools.org/display/WIPTSG/4.5+Get+and+Test+Concept+Subtypes+and+Supertypes)
* [4.8 Find Concepts](https://confluence.ihtsdotools.org/display/WIPTSG/4.8+Find+Concepts)
* [4.13 Get Concept Model Rules](https://confluence.ihtsdotools.org/display/WIPTSG/4.13+Get+Concept+Model+Rules)

### Service Examples

#### Snowstorm API

Validate concept definition:

```http
POST [snowstorm]/browser/{branch}/validate/concept
```

Response: JSON object with concept, descriptions, axioms, relationships.

Validate concept definitions (multiple):

```http
POST [snowstorm]/browser/{branch}/validate/concepts
```

#### FHIR API

No direct SNOMED CT expression validation services.

#### MySQL Example Database

* No direct support for expression validation, but can validate using concept model rules and expression constraints.

### Notes

* Language/dialect should be specified if service returns terms.

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