> ## Documentation Index
> Fetch the complete documentation index at: https://docs.metriport.com/llms.txt
> Use this file to discover all available pages before exploring further.

# communication_extension

Normalized `Communication.extension[]` property on the [Communication](https://hl7.org/fhir/R4/communication.html) FHIR resource.

**Primary Keys:**

* communication\_extension\_id

**Foreign Keys:**

* communication\_id - links to the [communication](/medical-api/handling-data/schema-v100/communication/base) table

<div style={{textAlign: 'right'}}><sub>† Metriport Platform added</sub></div>

| Column                       | Data Type | Description                                            |
| ---------------------------- | --------- | ------------------------------------------------------ |
| communication\_extension\_id | varchar   | Unique identifier for the extension row                |
| communication\_id            | varchar   | FK to the parent communication record                  |
| extension\_rank†             | int       | 1-based position of this extension in the source array |
| url                          | varchar   | Extension URL identifying the extension type           |
| valuestring                  | varchar   | String value                                           |
| valueboolean                 | bool      | Boolean value                                          |
| valuecode                    | varchar   | Code value                                             |
| valuedatetime                | datetime  | Datetime value                                         |
| valueinteger                 | int       | Integer value                                          |
| valuedecimal                 | numeric   | Decimal value                                          |
| valuecoding\_code            | varchar   | Coding code value                                      |
| valuecoding\_display         | varchar   | Coding display text                                    |
| valuecoding\_system          | varchar   | Coding system URI                                      |
| valuecodeableconcept\_text   | varchar   | CodeableConcept text                                   |
| valuereference\_reference    | varchar   | Reference value                                        |

**Related Tables:**

**Parent:**

* [communication](/medical-api/handling-data/schema-v100/communication/base)

**Child:**

* [communication\_extension\_vcc\_coding](/medical-api/handling-data/schema-v100/communication/extension_vcc_coding)