+.Pp
+The AltiVec Technology Programming Interface Manual also defines five additional length modifiers
+which can be used (in place of the conventional length modifiers) for the printing of AltiVec or SSE vectors:
+.Bl -tag -compact
+.It Cm v
+Treat the argument as a vector value, unit length will be determined by the conversion
+specifier (default = 16 8-bit units for all integer conversions,
+4 32-bit units for floating point conversions).
+.It Cm vh, hv
+Treat the argument as a vector of 8 16-bit units.
+.It Cm vl, lv
+Treat the argument as a vector of 4 32-bit units.
+.El
+.Pp
+NOTE: The vector length specifiers are extensions to the
+.Fn printf
+specification.
+Behaviour of these values for
+.Fn printf
+is only defined for operating systems conforming to the
+AltiVec Technology Programming Interface Manual.
+(At time of writing this includes only Mac OS X 10.2 and later.)
+.Pp
+As a further extension, for SSE2 64-bit units:
+.Bl -tag -compact
+.It Cm vll, llv
+Treat the argument as a vector of 2 64-bit units.
+.El