separator

In the object model this is RibbonSeparator.
A vertical bar used to provide a visual separation of controls within a group.
This also has a Title property which can be used to display text on the separator control when used with the following controls: OfficeButton menu, menu or splitbutton

<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui"> 
  <ribbon startFromScratch="true">  
    <tabs> 
      <tab id="CustomTab" label="My Tab"> 
        <group id="Group1" label="Group 1"> 
          <button id="button1" 
                  imageMso="ErrorChecking"/> 
          <separator id="Seperator1"/> 
          <button id="button2" 
                  label="Some Text" 
                  imageMso="LeaveReader"/> 
          <separator id="Seperator2"/> 
          <button id="button3" 
                  imageMso="OutlookTaskCreate"/> 
        </group> 
      </tab> 
    </tabs> 
  </ribbon> 
</customUI> 

Attributes (properties)

Callbacks (run-time)