Code that enables 16-bit code to call 32bit code,and vice versa.There are three different types of thunk;a flat thunk relies on a thunk compiler to allow 32-bit code to call a 16-bit dll and 16-bit code to call a 32-bit dll,a generic thunck enables a 16-bit application to load and call a 32-bit dll;and a universal thunk allows 32-bit code to load and call a 16-bit dll,allthunks are windowsbased ,but the type of thunk used depends on the windows version.