program ::= [ class_declaration ] ( ';' [ class_declaration ] )\stern .
Example: class MAIN is ...end; class TREE(T<ORDERED) is ...end 
The text of a program in SATHER-K is a collection of class declarations. It is specified by designating a class declaration K as the main class. K contains the main program which is a procedure main. K must be a concrete class (cf. 2.1).
Hint: The classes belonging to a program may be partially stored within the
same file or may be distributed across many files. The language does
not determine how to find those files.