Setting a prameter immediately after selection in search help

Hi

I would like to set a parameter 'X' immediately as soon as an entry in the hitlist of a search help, say 'A', is selected i.e just before the selected value is passed to the screen. I couldn't find any event for this in the call_control-step of search help exits.

The reason I would like to do this is because this parameter 'X' will then be used to influence the selection of another search help, say 'B'.

Can anybody help me out ?

Thanks