With the lock option, you can protect your selections.
You can lock a selection by clicking the lock icon \ in the selection popup. The lock prevents any changes from being made to that selection. You can neither change nor clear a locked selection. If you have locked a selection and then try to select excluded field values, the selection item will flash to indicate that the locked selection prevents the selection from being made.
You can unlock a selection by clicking the lock icon [ in the selection popup. When you have unlocked the selection, you can make changes to it, or clear it.