Re: only one of the element is req but not both...

> 1.I got 'dateDispatched' and 'dateDelivered' in my schema and i want to
> check wherein one of them is required but not both and the other should be
> empty.

You can't do this with W3C XML Schema alone but with embedded Schematron rules
it would be trivial. See [1] for an example.

> 2. Can i perform calculations in schema..
> its something like..can i set a field called 'TotalLines' empty to begin
> with,and then sum the lines received in xml doc and hence fill the above
> later.

No, this has to be done in the application.

Cheers,
/Eddie

[1] http://lists.w3.org/Archives/Public/xmlschema-dev/2001Nov/0049.html