Hi teseo, sorry just now, complicated day to me.
You try tell me it will working if exists a value in a hidden field selected? And that value can be controled by name or id. That selection can be dynamical by conditional (just thinking).
Let's suppose I have already that occult field pre selected value="1", with name and id named 'ascStartdate'.
Search was submited, '1' as value now, and search results.
Unless values are volatile after refresh page by link, I never tried do it before. Is needed keep values in a session?
Well, if is needed, I think function will check to compare the value of occult field (keep him in session), and will run without the last code line to s_startdate 'asc'. Revert again, using a direct link on menu, and add again the value="1" and keep the value again on same session.
Don't know how far it can be possible from my side.
Maybe I not understand yet your strategy, and can avoid my doubts.
Let me know when you can
Thanks for all your effort on help to solve this point.