"Trevor Shuttleworth" wrote...
....
OK, users can't be trusted.

The fundamental rule of application programming from which all good UI
coding flows.

Try:

=IF(OR(NOT(ISNUMBER(A10)),NOT(ISNUMBER(B10))),"nu ll point",
IF(OR(AND($A$2$B$2,A10B10),AND($A$2<$B$2,A10<B1 0),
AND($A$2=$B$2,A10=B10)),3,0)+--($A$2=A10)+--($B$2=B10))

+-- bits unnecessary, + alone would be sufficient.

However, too long.

=IF(COUNT(A$2:B$2,A10:B10)=4,3*(SIGN(A$2-B$2)=SIGN(A10-B10))
+(A10=A$2)+(B10=B$2),"TBD")