Incoming parameters

From AgileApps Support Wiki

Whether in a controller class invoked from a JSP page, or in a method invoked from a Rule, a variety of parameters are at your disposal:

Contains the name/value pairs for form fields and the identifier of the action button coming from a JSP page.
Includes the ID of the record the method was invoked on, the name of the object that contains it, and the values of fields in that record.