In an application written in the C programming language, a file or stream handler usually creates a function for each method. Your application accesses these functions through an array of function pointers the stream handler creates. An IAVIStreamVtbl structure contains the array of function pointers. A stream handler can assign any name it wants to functions it creates for the methods. The position of the function pointer in the structure implies the correspondence of the function to the method. For example, the first function pointer in the structure corresponds to the QueryInterface method. Your stream handler must provide all the functions of an interface.