system , control and info parameter

Hello All,

               I have couple of questions :

               1) What is the difference between system , control and info parameter ?

                2) Is it that we can do a search on system and info paramter and not on a control parameter ?

                3) I am configuring a value set for a selection parameter. I followed the following steps:

                       a) Define an info parameter and marked the flag for value set. Define the value set for this info paramter.

                       b) Define the parameter mapping for info parameter.

                       c) Configure the field as selection paramter where "EM attribute id"  as info parameter defined in step a.

                       d) Define user profile , set the selection parameter for a profile.

                     I am getting a dump saying "Type Not Found" in the Web UI.

                   If i am following the same steps for control parameter then UI is working fine but not fetching the result on search. Any pointers on this.

Thanks,

Shubh.