After the 2011 winter release Infusionsoft® made changes to the OrderItem.ItemType values.
Thanks to Pav-AML for providing the new values on the Infusionsoft® Community Forum:
I’ve pulled this out from the order type drop down list in the page source.
0 = Unknown Type
1 = Shipping
2 = Tax
3 = Service & Misc
4 = Product
5 = Upsell Product
6 = Finance Charge
7 = Special
8 = Program
9 = Subscription Plan
10 = Special: Free Trial Days
11 = Special: Order Total
12 = Special: Product
13 = Special: Category
14 = Special: Shipping
