[users] Indexing Mark Missing?

[DeWayne McCarty]

I have been using Writer for a couple of years. Today I opened one of my 
documents to proofing of the indexing. 
 
For some reason, the vertical graying marks that indicated where the text had 
been indexed were missing. (e.g.; Mark Johnson, there would be a Grey vertical 
line in front of Johnson). 
 
Is there some way to turn this mark on and off? I have the Carriage Return 
unprintable character visible.
thank you
DeWayne McCarty