# Create a shared dimension
This section describes how to create a shared dimension.
**Note:** Be sure to create one annotation to serve as the dimension key.
1. In the **Design** tab, click the **Flow** folder, and then double-click the **Shared Dimension** step icon. Alternatively, you can drag the step icon on to the transformation canvas.
2. Double-click the **Shared Dimension** icon to open the Shared Dimension dialog box.
3. Enter a name for the step in the **Step name** field.
4. If you are basing your new dimension on an existing shared dimension, select it from the **Shared Dimension Name** drop-down list of available shared dimensions, or enter a new name for it.
5. Select a source to associate your dimension from the **Data Provider Step** drop-down list.
The following steps are valid sources:
* Combination Lookup
* Database Lookup
* Dimension Lookup
* Insert/Update
* Table Output
* Vertica Bulk Loader
6. Enter a description of the shared dimension in the **Description** field.
7. Select available fields for annotation.
1. Click the **Select Fields** button to open the Select Fields to Annotate dialog box.
2. Double-click the fields in the **Available Fields** list to add them to the**Selected Fields** list.
For example, you might select **Year** to annotate as your dimension key and **Year**, **Month**, and **Week** to annotate as attributes Optionally, you can use the arrows to move one or more fields to the **Selected Fields** list.
3. When finished, click **OK** to close the dialog box. The selected fields now display in the **Annotations** table featuring the following columns:
| Column | Description |
| ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **Field** | Lists the names of the fields selected for annotation. |
| **Model Action** | Specifies which model action is being taken:- Creating attributes
|
| **Summary** | Displays a summary of that specific annotation. |
8\. Now you can create \[annotations]\(../Using%20the%20Annotate%20Stream%20step.md) for the selected fields.
```
1. To annotate a field, double-click it in the **Annotations** section. Optionally, you can select the select the field in the **Annotations** table and then select the **Edit** \(Pencil icon\) in the upper-right corner.
The Annotate dialog box appears for the selected field.
2. In the **Actions** field, click the drop-down arrow to select one of the following actions:
- **Create Attribute**. See [Creating attributes](../Using%20the%20Annotate%20Stream%20step/Use%20the%20Annotate%20Stream%20step/Creating%20attributes.md).
- **Create Dimension Key**. See [Create a dimension key](../Using%20the%20Annotate%20Stream%20step/Use%20the%20Annotate%20Stream%20step/Creating%20Link%20Dimensions%20for%20SDR/Create%20a%20dimension%20key.md).
3. You can use the **Previous** and **Next** buttons to navigate through the fields. When finished, click **OK** to continue or **Cancel** to close the dialog box without saving your annotations.
**Note:** You can remove a field from the **Annotations** section by selecting it in the table and then clicking the **Delete** \(X icon\) in the upper-right corner.
```
9\. Click **Apply** to save changes you made to an annotation. Click **OK** to continue or **Cancel** to close the dialog box.
This is an example of the Shared Dimensions dialog box.
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