I sometimes use the "#" as artficial sort key to move things on top if you have "Amazon.src" and "Amazon DE.src" as files than I use ""Amazon#DE.src" to bring in into the #1 pos.
But in this menu I noticed that the result was different.
Amazon became something like a virtual folder and the action is called DE.
Now I've played a little bit with that and it works fine especiall if you many src's.
If you want to use & in the title like 1 Cover # Search by title && artist .src you have to use & twice.
But here's a small picture attached, where I used 2 Cover Amazon # 4 DE by Title [BUP].src
I couldn't find any hint in the docs so made the post here because it has nothing to deal with the dev. inside sourceframe, it's just usability. Maybe you move this topic to where it should belong but I thought it would be useful to start here.