Scheduler-mode attribute in the Timing Parameters system table of G2 is real-time, indicating that G2 time is passing in relation to true clock time. region: A named group of one or more icon layers. All the layers in a region have the same color. You can use the change action to change the color of any named region.
Region 1: A block of memory used by G2 to hold items and non-symbolic values.
Region 2: A block of memory used by G2 to hold symbols and related internal data.
Region 3: A block of memory used by G2 to hold any external images used in icons and as the backgrounds of workspaces.
Region Indicator: In the Icon Editor, a display that names the region (if any) to which the current layer belongs.
relation: An actual association of a particular kind between two items in the current KB. Contrast with relation definition.
relation definition: The definition of a kind of association between two classes of items. A relation definition has a name, cardinality, a first class, a second class. A relation definition can also be symmetrical. A relation definition can optionally name a kind of relation that is the inverse of this relation definition. Contrast with relation.
relation object: The second class in a relation definition.
relation source: The first class in a relation definition.
relative time-stamp: A GFI time-stamp format that consists of a non-negative integer that specifies a number of seconds since the base time of the file.
remote data server: A process external to G2 that supplies G2 with data or that accepts set actions from G2. A remote G2 can be a remote data server, for example, as can a G2 Gateway interface. See Also G2 Gateway standard interface.
remote window: The visible window that is a client of a Telewindows process connected to a running G2 process. Contrast with local window.
rendezvous failure: The inability to restore membership in a permanent-membership list or array, or participation in a saved permanent relation, when a saved KB is reloaded.
representation: The appearance of an item, which is of a particular representation style.
representation style: One of several forms in which class of items appear. Each system-defined class in G2 has a representation style. A class's representation style determines whether items of that class appear as icons, text boxes, displays, connections, and so on.
request mode: A GFI input mode in which GFI provides a KB with data when the KB requests it via data seeking.
required module: A module that contains items required by another module.
reserved classes: System-defined classes in G2 that can be inherited only by system-defined subclasses. An example of a reserved class is
VARIABLE. reserved symbol: A symbol that cannot serve as a user-defined name in G2. In the Text Editor, the prompt
any unreserved-symbol indicates where you must enter a user-defined name. reserved words: Symbols that cannot be used as names or symbol values in expressions.
root class: The topmost class in a class hierarchy, or the topmost class of interest in a subset of a class hierarchy.
rule: An item whose text expresses a programmatic response to a set of conditions. A rule's text contains a two-part statement, which can take one of several forms; for example:
when fire-alarm is sounding then invoke fire-safety rules. G2 invokes rules using several different mechanisms. rule invocation: A executing copy of a rule. When G2 invokes a specific rule, G2 creates one rule invocation. When G2 invokes a generic rule, G2 creates one rule invocation for each item or value that meets the conditions specified in the generic reference expression in the rule's antecedent. Consequently, several invocations of the same generic rule might execute simultaneously.
run-state: Whether the current KB is running, paused, or reset. Changing the current KB's run-state affects the KB's knowledge.
run-time validation: Instructions that G2 includes, by default, in a compiled attribute. When the compiled attribute is invoked, evaluated, or referenced, the attribute's run-time validation instructions cause G2 to verify whether the attribute's own assumptions about the referenced item-that is, its name, its class, and so on-are still true.