- These events arise when the of item is equal to the of an item, or the value of an expression set in this when block. Optionally it checks device armed status by logical AND operator with isItemState condition. An expression can be used instead of the constant item value. These events also arise when the data source is a device/item group, the event is stateless. It arises every time the condition is true, no matter which value of an event was previously. See Stateless comparison.