Title: Time for MathML?
It is definitely is worth taking look at - but I would hesitate to suggest basing XACML standard on a standard that we do not support in its entirety. It will just add confusion..
That is the same issue I have with using XML mechanisms for type checking - if it is not 100% sufficient, then having it just adds complexity.
One proposal on data types: Why do not we define separate XACML data types (like xacml:integer, xacml:date) and require that any compliant application should provide implicit unique conversion to this data types from any XML schema data types. That would have the advantage, that the implementation may define this data type internal representation broad enough, so it can accommodate some future, or custom data types, that can not be uniquely transferred to any particular XML schema data type. It will also make for a more compact core schema.
unrelated rant..
..Anecdote from my past experience - we had to define data interchange format for a very large future satellite experiment. Some folks came up with a bright idea of using schema capabilities to enforce good structure (from physics prospective) of the event - needless to say they are still struggling to have one fully compliant data tool off the ground.. I feel we in a bit of the same mode - trying to enforce policy consistency, with XML capabilities.. not sure if it is worth trying..
