JML (the Java Modeling Language) is a behavioral interface specification language that can be used to specify the behavior of Java modules. It combines the design by contract approach of Eiffel and the model-based specification approach of the Larch family of interface specification languages, with some elements of the refinement calculus.
As of Fedora 8, the jmldoc tool no longer works. It requires the tools.jar file from a JDK 1.4 installation, and there no longer is such an installation on Fedora 8. All you jmldoc users will just have to wait until the JML team fixes the problem with JDK 1.5 and later tools.jar files.