# SNOMED CT Importing

## Importing a SNOMED CT release or extension

The import functionality is restricted to users with *administrator* roles.  The import format needs to follow the standard RF2 format specification.

### Starting the import wizard

Go to `File > Import... > Snow Owl > SNOMED CT Release from RF2`, and click **`Next`** to bring up the Import Wizard.

### Selecting the release version to import

Select which version you want to import:

| Release format | Description                                                                                                                                                                                                                                                                                                                    |
| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **Delta**      | All component versions created since the previous release. Only components that were changed or added are included. Delta versions are the fastest way to update your terminology, but you must have previously imported a snapshot or full release.                                                                           |
| **Snapshot**   | Most recent version of every component. Even components that did not change are included. If you don't work with historical information, the snapshot release might be sufficient for your needs. It can be imported in an empty database or if there is already an older SNOMED CT release.                                   |
| **Full**       | Every version of every component ever released. The full historical information is included on every component. If you need historical information, you should start out with the full release, and use the delta version to update your terminology. An import is only possible if there is no SNOMED CT content in Snow Owl. |

{% hint style="info" %}
If you are working with a standalone version of Snow Owl, the SNOMED CT release is already part of the application and you don't need to run an import. Once a new release comes out, it's sufficient to run a delta import to update the existing content. For this reason, only the delta import is enabled, the other import options are disabled.
{% endhint %}

Tick the checkbox at the bottom to **Create version for each imported effective time value.**

### Selecting the import files

Click the **`Browse`** button to select your archive file.

### Selecting Reference Sets

Check the Reference Sets you want to import from the list. You can add a new Reference Set file to the list manually by clicking on the **`Add`** button and selecting the Reference Set file to import. To exclude a Reference Set from the import uncheck the box. Click **`Finish`** to start the import.

### Running the import

During the import, the **Remote Jobs View** will keep you updated on the import process. The import process will analyze the description logic basis of the ontology and create several types of indexes, including a semantic cache. Depending on the number and size of the input files you selected, the import can vary between a few minutes (delta) and several hours (full release).

### Reviewing results

Once the import is completed, the differences between the original ontology and the newly imported release are accessible. You can review details about the changes for each component by right-clicking on the information in the Remote Jobs view and selecting **`Review Results`**. The details will be displayed.


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