OK, I can now make folders!!

I used a command line like this:
mobi2mobi --outfile wsj4.mobi --booktype "257 - NEWS" --title "WSJ" kitty.mobi
to make the book Kitty Goes to Washington appear in the same folder as an actual enews file called (you guessed it) "WSJ" (The other "WSJ" file was created by Mobipocket Web Companion 4.9 and so has booktype "257 - NEWS" automatically).
The only problem is that since both have the title set to "WSJ" (the folder name) both appear as "WSJ" when you open the grouping.
On a real Kindle, something else is used to get the name inside the grouping. I know this both because the real newspapers have a "date" after the name and because one of my subscriptions ("Opinionated") changed the name that appears there after a couple of weeks and the older ones appear as one name, the newer ones as another.
The problem is I don't know what attribute the Kindle looks to to override "title" when show the members of the group?
Any ideas?
Igorsk, is it visible in the Java code?