Nothing out of the box.
If you really want to do that at a front-end lever only then JS is what you look for. Just be ready to fight and struggle with it. The values of the prompt are loaded dynamically in the background, if you manipulate them difficult to know how the OBIEE code will react and if it will load doubles or whatever.
If unlucky it will also lose the real value and start using the shortened version for filtering, which obviously doesn't work as that short form doesn't exist for real in your data ...
Can't you just add an extra column to your dimension with a short form of the same values? At least it will then be normal standard OBIEE, using the short column in the prompt instead of the long one
Gianni, I think your idea with the extra column just might make it work for me. As always, thanks for the great insights, you've helped me come a long way ever since I have been using OBIEE.
You are welcome Andrew. In case you will have time to test it and works and/or do not find anything else useful come back to close the thread