Here is what I have done depending on the need.  

Create a dummy code but left the description of that code blank.  You still get the colored bar but its blank without "No Phase" words printed.

or

Make a filter to say where code does not equal blank and those activities and bars will not show up at all (provided you also have "hide if empty" checkbox on the group and sort).  No dummy code needed.

Solution

create a new filter

select    if    what ever code       is not equal to

just leave the value blank do not put anything in it

Zoltan Palffy