Default an Enum for a control

Im trying to default the ‘create release Product’ form so that when the client opens it, the Product Subtype will show Product master, not Product. I just dont know how to write the code to set this as the default. Im still new to AX and im learning so if anyone can help that would be greatly appreciated.

Never mind i found that in AX 2012 on the control combobox there is a field in the properties that is called Selection. Selection is used to set the controls initial value, in my case Product Master.