nil is a pointer value which is compatible with all pointer types. This constant can be assigned to any pointer variable to indicate that the variable doesn't point anywhere, and any pointer variable can also be compared with nil.
As an extension to Standard Pascal, nil is also a object value which is compatible with all object types. This constant can be assiged to any object reference to indicate the the reference doesn't point at any object, and any object reference can be compared with nil.
Operating Systems: All Standard Pascal: Yes