put https://yourServer.jamfcloud.com/JSSResource/mobiledevicegroups/name/
One or more mobile devices can be added by using "mobile_device_additions" instead of "mobile_devices". One or more computers can be deleted by using "mobile_device_deletions" instead of "mobile_devices".
<mobile_device_group>
<name>Sample Group</name>
<is_smart>true</is_smart>
<criteria>
<criterion>
<name>Last Inventory Update</name>
<priority>0</priority>
<and_or>and</and_or>
<search_type>more than x days ago</search_type>
<value>7</value>
<opening_paren>false</opening_paren>
<closing_paren>false</closing_paren>
</criterion>
</criteria>
<site>
<id>-1</id>
<name>None</name>
</site>
</mobile_device_group>