Release 10.1A: OpenEdge Getting Started:
Object-oriented Programming

> ## Comparing objects

> You can compare two object references for equality using the equals operator (`=`), which checks if two object references are actually referencing the same object. The object references can be equal even if the object references have been defined for different classes in the class hierarchy. Two object references are also equal if they are both the Unknown value (`?`).

> The following example demonstrates the use of the equal operator usin the two object references, `rSuper` and `rSubClass`:

>     DEFINE VARIABLE rSubClass AS CLASS SubClass NO-UNDO.
>     DEFINE VARIABLE rSuper    AS CLASS SuperClass NO-UNDO.
>     rSubClass = NEW SubClass ( ).
>     rSuper = rSubClass.
>     IF rSuper = rSubClass THEN
>         MESSAGE "they are the SAME".

> The `MESSAGE` statement will indeed be executed, demonstrating that `rSuper` and `rSubClass` are equal even though they are defined as different classes in the class hierarchy.

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