Like a variable, a property holds a value of a built-in type or user-defined type, but it also has built-in accessor methods get() and set() that are used to access the data in the property. This is useful because you can define a property to be read by another part of the application, but only to be set by methods of the class. In addition, you can add code to the get() and set() accessor methods to customize how the property value will be read and set. For example, you can implement the set() accessor method to transform a PostalCode value into a standard format.

Note: A best practice is to define properties as PUBLIC for reading and PRIVATE or PROTECTED for setting. PACKAGE-PRIVATE and PACKAGE-PROTECTED allow package-level protection. This enables you to control how data is accessed by code from other parts of your application. Most of the data members you add to an ABL class are defined as properties.
See also: