Roberto is asking the same question I am asking:
There are many proposal definitions of Open Format,[…]So, what about a “Free Formatâ€ definition?
I have explored new terms with the list discussion in July and came up with the term I used on the brief paper I wrote on the topic: Open Unencumbered Standard. It’s ugly, though. I personally don’t like the term Free Standard because I really don’t want to start again the ‘open is not free’ debate: it has bored me to death already for software and I wish we could get over it.