. . . This modification to his formula seems to work...

=SIGN(COUNTIF(C7:U7,0)-(L7=0)=0)*(COUNTIF($C$8:$U$8,0)-($L$8=0))

It may, but what I should have written was

=NOT(COUNTIF(C7:U7,0)-(L7=0))*(COUNTIF($C$8:$U$8,0)-($L$8=0))

They are equivalent...

SIGN(FALSE) = SIGN(0) = NOT(1)

SIGN(TRUE) = SIGN(1) = NOT(0)

Whether using the SIGN or NOT approach, I like the overall construction of
the formula... especially the

COUNTIF(C7:U7,0)-(L7=0)

construction which guarantees that it can't evaluate to the troublesome -1
value that would cause NOT(-1) to be a problem. Nice insight there Harlan.

Rick