position_flag (USHORT) - input

The flag that indicates where the caller wishes the data chain element to be linked into the data chain. A value of 0 places the element at the head of the chain. A value of 1 places it at the tail of the chain. A value of 2 indicates that the element should be linked in front of the chain element pointed to by the existing_element_ptr argument. A value of 3 indicates that the element should be linked after the chain element pointed to by the existing_element_ptr argument.