Incorrect COVAR constraint

COVAR has the constraint

Constraints: Each sequence must contain 1 number at least. The number of numbers in n1 and
n2 must be equal.

Now suppose A1 to A4 contains 1;2;3;4
and B1 to B4 contains 1;2;x;4 then according to the constraint COVAR (.A1:.A4;.B1:.B4) should be an error, but in OOo and Gnumeric it returns 1.55555556. (basically OOo and Gnumeric seem to drop the incomplete records, ie. it drops the values in A3 and B3.)

Are we truly intending to use a definition contrary to the common implementations in place? Note that OOo and GNumeric's behaviour is much more reasonable.