The Expr1 element is used within an IfEqual element as part of a comparison with the value contained in an Expr2 element. The Expr1 element contains the CAML expression that is evaluated to determine the course of action for an IfEqual statement. The expressions can be any set of CAML elements that render text, or they can be other conditionals.
The following example evaluates two expressions, and if they are equal, it conveys a holiday greeting, but if not, it conveys a different message.
<IfEqual> <Expr1><Today/></Expr1> <Expr2>10/31/2000</Expr2> <Then>Happy Halloween!</Then> <Else>Just another day</Else> </IfEqual>