Abstract, a method modifier

Syntax:
DECLARE ABSTRACT SUB Foo

In a normal Lemick class any method prototyped with Declare statement is an abstract method thus causing the containing class to became abstract. For an extern class the prototyped methods are considered as normal with their body declared somewhere else. To define the particular method in an extern class as an abstract you must place Abstract keyword just after Declare.
For the classes extending a abstract class with the abstract methods the compiler will require implementation of all the abstract methods unless the declared class is abstract itself.