[Koha] Item Type Defined in MARC

Good Morning All Does anyone know where in MARC is the item type defined? In my exported data from Follett I don't see anything that looks like the item type codes that are in Koha. Thanks Ed Edward J. Roche Network Administrator Solanco School District 717.786.2151 x2437 "At the End of the Day, Did You Play to Win or Not to Lose?"