The VLE (Variable Length Encoding) instruction set is an extension to the instruction set specified in the Freescale Book E Implementation Standard (EIS). Not all Power Architecture processors have VLE capability. Refer to the manufacturer's documentation for the processor you are targeting. For information on the Book E and VLE programming models, see EREF: A Programmer's Reference Manual for Freescale Book E Processors , published by Freescale Semiconductor.