I no nothing about rox-filer and just saw it as a file manager trying to associate file types with programs and maybe i should have kept it shut.
I was answering straight to the poster as a suggestion, sorry for not leaving quotes, but it was not meant against your definitive answer from someone who knew, being you
So its was not meant like "my surgestion is a standard your answer is not..."
Besides that we speak of two different things now one being a shell var and the other being field code for file managers.