When testing a rule, you may now enable debug mode by clicking the Debug button. This produces output that identifies each element, is executed by the system, and shows the return value from that element.
For example, consider the following block of code:
<Expr op='concat'> <Expr value='First'/> <Expr value='Second'/> </Expr>
When evaluated in debug mode, it would result in the following output:
<Expr op='concat'> <Expr value='First'> </Expr> result value <First> <Expr value='Second'> </Expr> result value <Second> </Expr> result value <FirstSecond>