Token defaults not working

The documentation claims that there is a way to include defaults, but that functionality doesn't actually exist:

http://wiki.civicrm.org/confluence/display/CRMDOC43/CiviMail+Reference

"By default, if there is no value for a token field, it is replaced with a blank string. This can be overridden in the document as follows:

Hello

{contact.first_name|anonymous contact}

!"

But actually attempting this gives the error:

"syntax error: unrecognized tag: contact.postal_greeting|user"

BTW although the documentation should be updated, it would be very nice to have this functionality.