Ruby::Marshal::Class

“c” represents a Class object, “m” represents a Module and “M” represents either a class or module (this is an old-style for compatibility). No class or module content is included, this type is only a reference. Following the type byte is a byte sequence which is used to look up an existing class or module, respectively.

Instance variables are not allowed on a class or module.

If no class or module exists an exception should be raised.

For “c” and “m” types, the loaded object must be a class 

or module, respectively.