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

# Dates

Elation's platform supports storing a variety of longitudinal patient data. Here is some info about dates you'll find across the API.

## Timezones

Data provided over our API should be assumed to be in UTC.

## Datetime format

Our API accepts most [ISO 8601 formats](https://en.wikipedia.org/wiki/ISO_8601).

### Examples:

```
2023-04-04T23:30:04+00:00
2023-04-04T23:30:04Z
20230404T233004Z
```

And produces dates that should follow the format:

```
%Y-%m-%dT%H:%M:%SZ
```

### Example:

```json theme={null}
{
	...
	"document_date": "2023-04-09T18:41:23Z",
	...
}
```

## Common Datetimes

There are some datetimes that are common across a lot of Elation's API resources. It can be useful to understand what each describes.

Some specific resources will include

* `document_date`
  * The datetime this document "happened" in the world. Sometimes changeable in-app to help provider's better represent a patient's longitudinal history. Often the same as `chart_date` below.
  * e.g. A CCDA import includes data about a visit that happened sometime in the past will have a document date that represents when that visit occurred.
* `chart_date`
  * The datetime this document appeared in the patient's chart.
  * Often the same as `document_date` above but can be different if the document represents historical data.
* `signed_date`
  * The datetime a document was signed by a provider.
* `created_date`
  * The datetime when a resource was created in Elation's platform. Will often be the same as the `chart_date` and `document_date` above.
* `deleted_date`
  * Most resources in Elation's platform are "soft" deleted to ensure we can recover data and provide more accurate reporting.
  * The datetime this resource was marked as deleted.
* `last_modified_date`
  * The datetime when this resource was last updated.