The Microchip specification for VHHR is Vdd+3.5v as minimum, with 13.5v as maximum BUT it varies from PIC family to PIC family. Some have a 10v minimum and 12v maximum. You must refer to the Programming Specifications for the PICs you want to use... also check here...

http://www.microchip.com/stellent/id...GE&nodeId=1407