Hi Edward:
If there are no "W", "X" or "Y" Items, the Filter would be: Item Code <= "UZZZZZZZZZZZZZZZ".
But from the way you phrased the question, there are likely Items in the range "W", "X" or "Y". You would need logic like:
Item Code <= "UZZZZZZZZZZZZZZZ"
OR
(Item Code >= "W000000000000000" AND Item Code <= "YZZZZZZZZZZZZZZZ")
The part in brackets is "nested". You can do that with GridView but not with Filters.
Therefore, the solution would be the same as one of your recent posts - use Report Group or an Optional field to distinguish the 2 classes of Items.