Most framework objects contain sets of properties. Properties represent information that is available to a driver. From the driver's perspective, some properties are read-only and some are read/write.
For each readable property, the framework defines a "get" method that a driver can call to retrieve the property's value. Each "get" method returns the current value of the property.
For each writable property, the framework defines a "set" method that a driver can call to modify the property's value. The driver supplies the property's new value as an input parameter to the "set" method.