This event occurs when the user clicks the up arrow of an entry field with the SPINNER style. The program responds to this event by incrementing the value of the entry field. You are not limited to incrementing by 1. You may increment the value of the field any way you want by inquiring the field's current value and then modifying it to have the desired value.
If the entry field has the AUTO-SPIN style, you can set EVENT-ACTION to EVENT-ACTION-FAIL in response to MSG-SPIN-UP to prevent the control from incrementing the value itself.