collect data statement within a procedure or method; using the update action to explicitly update the variable.data service: The process of obtaining a value for a variable from the variable's data server, which can either be internal or external to G2.
data-driven processing: A technique of initiating processing by forward chaining to "if" rules when a variable receives a value. G2 invokes the rule if its antecedent refers to the variable. If the test in the consequent of the rule is true, the actions in the consequent occur simultaneously. Data-driven processing starts a new process. Contrast with event detection.
dependent module: A module that contains instances, whose class definition is located in a lower-level module in the module hierarchy. A dependent module always requires the lower-level module in order to function. Contrast with independent module.
dialog: A feature of end user interfaces that allows you to edit the attribute values of objects through a familiar user interface, which consists of type-in boxes, check boxes, and push buttons. You use the GUIDE utility to create dialogs.
direct superior class: The class from which a user-defined class inherits its definition. A class can have one or more direct superior classes. See also inheritance and multiple inheritance.
direction of flow: A characteristic of connections that determines the direction in which data can flow along the connection. You specify the direction of flow when you declare the stubs of a class.
dynamic display: A dynamically generated graphical attribute readout, which you create by using the G2 Dynamic Displays (GDD) utility.