Initial import of "Joos":

Joos is an acronym for Java's Object-Oriented Subset. JOOS is a
proper subset of Java which is used to teach students about compilers.

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+Joos is an acronym for Java's Object-Oriented Subset. JOOS is a 
+proper subset of Java, defined as follows:
+  * its context-free syntax is restricted to the following grammar;
+  * subclassing must not change the signature of a method;
+  * declarations of locals must all be in the beginning of the statement
+    sequence in a block;
+  * protected fields cannot be accessed from without the class or its
+    subclasses; and
+  * every path through a non-void method must return a value.
+
+In addition, JOOS defines a concept of extern classes, which provide 
+a convenient interface to the Java libraries without requiring the 
+compiler to parse Java class files.
+
+It defines a class name and some method signatures, along with a file 
+name that is guaranteed to provide the implementation. The JOOS compiler 
+will implicitly trust this specification. If it is incorrect,
+then the compiled JOOS class file may fail at class loading time.
+
+JOOS is used for teaching students about compilers.