Programming Guide - Actian

local variableLocal variables contain data that is associated with a specific frame, procedure,method, field script, or event block.macro variableMacro variables are substitution parameters that you can define and give avalue.menu eventMenu events are events triggered when a user selects a menu item.menu item variablesField and menu item variables are variables that are associated with the valuein a field or menu item. These variables are not associated with the objectrepresented by the field or menu item.named constantA named constant is a literal value to which you give a name. You can thenuse the name in place of the constant in any 4GL expression.nullA null is an undefined or unknown value. A null is not the same as a zero, ablank, or an empty string.null constantA null constant is represented by the special keyword null. You use thiskeyword to assign a null to a nullable variable or database column.objectAn object is a compound data structure that holds values that you canmanipulate.PaletteField objectPaletteField objects display a list of values, represented as images, from whichthe user selects a single value.polymorphismThe process of a subclass's method superseding the behavior of an identicallynamedmethod defined for a superclass is called polymorphism.496 Programming Guide