Specifying variable type in MathML

I'm writing a  quation evaluator which takes equations in form of MathML
content markup. 
It can operate on java objects,functions and constants. 

I have some confusion regarding specifying a data type to a external
variable.
Can I extends types defined in MathML?

For example I have a variable 'd' of type "Date" and I want to check if date
is equal to some other date.
Assuming I can process <eq/> correctly depending on data type, is the
following representation correct?
<apply>
<eq/>
<ci type="Date" definitionURL="URI of definition of Date">d</ci>
<cn type="Date" definitionURL="URI of definition of Date">03-05-2002</cn>
<apply>

or I should declare the variable to  be of "Date" type?
<declare type="Date" definitionURL="URI of definition of Date">
<ci> d </ci>
</declare>


Regards
Kamlesh

Received on Sunday, 5 May 2002 15:34:25 UTC