Which I think is better since YourField Mod 2 by itself isn't really a boolean expression and just relies on the fact that any non zero values is considered true.
I actually borrowed it from an excel forum and it seemed to be correct, but as you say it doesn't account for non 0 null values. It's too hot and Monday, that's my excuse...
But that placement is correct with the condition being YourField Mod 2 which is true when the YourNumber is odd. YourField Mod 2 = 0 is true when YourNumber is even.