Using the Use Constant Standard Rule
The Use Constant standard rule enables you to move a constant value to the specified field and indicate a qualifying relationship with another field.
Constants are used in maps to hold information that is needed later in the map, either for an output field or a conditional statement. Typically, constants move a constant value to the specified field or generate qualifiers (to indicate a qualifying relationship with another field).
Typically, constants are used to load common data into each positional record on a map. You create the constant and name it. You can hard code (type) a value that is loaded into the field that uses the constant. Or you can store information from a field in a constant by using an extended rule. However, to use a constant (the information that is stored in it), you must use a standard rule.
For more information, see: