Try this on PERF INIT Page 2/3:
— 5L
-- Cruise winds at the anticipated cruise altitude are entered
at 5L. Data entry formatting and syntax is consistent with entry
of wind magnitude and direction on other FMS pages. The
default CRUISE WINDS value is zero.
In addition, the altitude is entered before the cruise wind is
accepted. Entering *DELETE* returns the default value of zero.
— 5R
-- 5R is associated with 5L and gives the pilot the ability to
specify the cruise wind altitude. Data entry is consistent with
entry of cruise altitude on other FMS pages. The default value
is set to zero. In addition, the FMS gives the pilot the ability to
enter winds from altitudes of --1300 to 60,000 feet.
See if it helps.
Cheers!