Inconsistency with XLL in custom functions: when using matrix arguments, do not pass blanks as 0

1. Create a custom function with one argument.

2. For the argument, specify type: 'any', dimensionality: 'matrix' and repeating: true.

3. Invoke this function like =MYFUNC("A",M1,"B") where M1 is an empty Excel cell.

4. Observe the passed in arguments in the debugger: the second argument will contain zero instead.

Second experiment:

1. Invoke this function like =MYFUNC("A", 0, "B").

2. Observe the passed in arguments - they are the same as in the first experiment.

Actual result:

We cannot disambiguate legitimate zeroes from empty cells.

Expected result:

We expect an undefined value instead of a zero in the first case, or some additional metadata to disambiguate.