Hello pcouderc,

My conclusion is that false is not always 0...

No, indeed. The definition of false in Perl is given in perlsyn#Truth-and-Falsehood:

The number 0, the strings '0' and "", the empty list (), and undef are all false in a boolean context. All other values are true. Negation of a true value by ! or not returns a special false value. When evaluated as a string it is treated as "", but as a number, it is treated as 0. Most Perl operators that return true or false behave this way.

Hope that helps,