You might try FTN::Bit_flags from CPAN.

I don't see how this is particularly relevant to my needs.

When one assigns a value to a scalar, $x, by doing say:

$x = -17;
or
$x = 1.414;
[download]

perl ascribes some numeric flags to $x, and those flags (which vary for different types of numbers) are not readily visible.
My main interest was in the ways that we can make those flags visible to the program - and it's not apparent to me how FTN::Bit_flags can help in that regard.
Looks to me that this module is more about manipulating bit flags, which is not my concern here. (I'm just trying to get a hold of the damn things ;-)

Cheers,
Rob