OK, I understand how to apply the "WHERE", but I am not seeing how I am going to apply this to work with 2 separate layer lists.
Layer List A = Units, Layer List B = Years
User selects, via checkbox, UNIT A, UNIT B and UNIT C, then the user goes to LayerList B and selects Year 2010, the map populates with the appropriate selected data. Then the user decides they want to remove UNIT C, so they unselect it from Layer List A, and is now viewing data for the remaining units in the selected year.
This is how it has been requested to set the map up, so the user can see all their choices in front of them without having to use a drop-down or type what they are looking for in a search box.