[plt-scheme] classes, contracts, modules

A few questions about the class library:

- The grammar in 13.3 for contract-expr has "object-contract" in the font
of a non-terminal, but I believe that's supposed to be a keyword?

- Chapter 13.3 claims to be about class and object contracts but has no
information about class contracts. Is it possible to attach a contract to
a class?

- Is it possible to provide a class from a module without providing the
ability to construct an instance of the class? Cf. abstract classes or
classes with private/protected constructors in Java.

Thanks,
Dave