Editing the Subject textbox on SSRS Email Standard Subscription

Hi

Does anyone know if it is possible to edit the subject text box of a Standard Email Subscription so that it contains report variables other than the default Globals and if so, how?

Basically I want to add a value field from the report I'm emailing into the subject line. I've already discovered that you cannot use the rest of the Global variables in the subject line other than the default @.ReportName and @.ExecutionTime.

The variable I want to add is in the report dataset.

Any help would be greatly appreciated.

Thanks

RW

Sorry, I don't have the link to the site I saw this on, but I did read that @.ReportName and @.ExecutionTime are the only 2 parameters available.