VF - Vdata Field Interface

VFfieldesize/vffesiz	Returns the size, as stored on disk, of a vdata field.
VFfieldisize/vffisiz	Returns the size, as stored in memory, of a vdata field.
VFfieldname/vffname	Returns the name of a vdata field.
VFfieldorder/vffordr	Returns the order of a vdata field.
VFfieldtype/vfftype	Returns the data type of a vdata field.
VFnfields/vfnflds	Returns the total number of fields in a vdata.