It's in a vhost template and the info says this...
Syntax: It can be an absolute path or path relative to $SERVER_ROOT, $VH_ROOT, or $DOC_ROOT. $DOC_ROOT is the default relative path, and can be omitted.
So I assumed I can leave that blank as $DOC_ROOT is the default value.
How about the Example page, still there? There is a /protected/ context which has a such case, can you do a test?
If still not work, you may raise a ticket in our system and our support team may help .
Thanks
David