Variables are temporary sub documents that can be used at runtime to store data while an agent is processing its RuleBase.
This enables you to separate out information if required to make it easier to understand and implement the required functionality. For example, if you are making a call to a remote service, you may want to create 'request' and 'response' Variables to store the messages sent to and from the service.
The Variables section towards the bottom of the RuleMaker screen displays all the Variables that are currently defined.
A new Variable can be defined by entering the required name in the text box, and clicking the Insert button. which will add it to the main list above.
A Variable can be removed by clicking on the appropriate 'cross' button at the right hand side.
When you wish to refer to a Variable in an XPath, you must use the name of the Variables preceded by a $ sign, e.g. '$request' and '$response'. This tells the engine to look in the appropriate Variables document rather than the main FactBase.
If you wish to create a complex XPath looking into a Variables, but with predicates against the FactBase, you must prefix your XPath section looking into the main FactBase, with '$factbase'. This is so that the engine can be absolutely clear as to which parts of the XPath should be checked against the Variables, and which against the main FactBase.