I wanted to set up a visual filter for anarthrous nouns, but the forum threads that I found on the subject suggested that it was not possible in Logos 4/5.
However, I have found a solution. Essentially I used the first line of the filter to highlight all nouns (underlined in green). I then used a second line to cancel out that highlighting (underlined in white, assuming a white background) for arthrous nouns.
I'm posting in case it is of use to someone else.
