++ for trying to make perldoc -X work. -- for suggesting XML. Several -- for that, even.

POD has a powerful advantage in that it is light on the markup. You can read POD without requiring a 'viewer' to make visual sense of it. XML is almost the antithesis of that ease of use.

Perhaps you could rejigger perlvar in the same manner as perlfunc, to regularize the usage. You have the power...