Learn how to build a sub rule by selecting segments, dragging decision points, entering values, and configuring options in the Request Header dialog box.

1. Select the Advanced segment title.
2. Drag the Referrer decision point to the canvas. The Request Header dialog box displays.
3. Enter Facebook in the Value text box.
4. Select the plus (+) icon in the top right of the Request Header dialog box. The Add Decision dialog box displays.
5. Select the Referrer decision node. You can locate the Referrer decision node in either of the following ways:
   1. Scroll to the Advanced segment title.
   2. Enter the term in the Search box; as you enter characters, the matching decision nodes display.
      A tab is added to your Request Header dialog box.
6. Enter Twitter in the Value text box.
7. Select the Or radio button from the Type options.
   Note: Selecting the Or radio button means that if the end user came from either Facebook or Twitter, they follow the Yes path in your rule. You can add further tabs for each social referrer you want to check, as described above. For further information on the recommended values to use for common referrers, see the Referrer Values topic.
8. Click Save.
   The nested decision node is added to your rules canvas.

   Now you can add outcomes and connect your nodes to finish defining the sub rule.