Boolean_Value : sub_class_of : Type_Item

This item represents a particular type of constant value that can be used as the object of connections. For example, in the statement "SallySinger paysTaxesOnTime-Is 'True'", "true" is the Boolean constant object of the connection. Sometimes the value of a Boolean-type constant can be input by selecting a specific web-page control, and other types it has to be typed into a text-entry box. When typed, only the words "true" or "false" should be used, although the capitalization ("true", "True", "TRUE") doesn't matter. In addition, for connections that use properties that express a true/false state but whose objects are Items rather than constants, the system provides the built-in Items "Value_True" and "Value_False" that can be selected as a relationship's object.

This relationship is used to connect two items, both representing classes, indicating that the subject item is a sub-class of the object item. For example, the connection "Ships is a SubClass-Of Vehicles" links the two class items, and makes the statement that "Ships" are a more specific kind of "Vehicles". Once this connection is established, the system will behave as if everything that is true about "Vehicles" is also true for "Ships" (although not vice-versa). For example, if another property is defined such that its object items are required to be instances of the "Vehicles" class, then having this connection allows instances of "Ships" to be used as well. But, another property whose objects are required to be "Ships" is not affected, and other "Vehicles" still cannot be used.

This category item is the class that contains all items representing possible "types" for the values of property objects that are constants (rather than other items). For example, in the connection "SallySinger sBirthdayIs 'March 10, 1977'", the object of the "sBirthdayIs" property is a date constant. The type for data constants is represented in the system by the item "Date_Value", which is one of the members of this class. All of the constant types that the system is capable of handling are represented by members of "Type_Item". (Note that, if the type of information you want to use as a constant object doesn't have a matching "Type_Item" member, you can use the generic "String_Value" type.)