MRJ is Apple's implementation of the Java VM and runtime environment, based on Sun's JDK 1.1.3 specification. It lets you to execute Java applets and applications on PowerPC and 68040 computers running Mac OS 8.0 or later. MRJ, which features a solidification of shared libraries and other scheme software files, supports all the new Java features introduced in Sun's JDK 1.1, including JavaBeans, Internationalization, Security and Signed Applets, AWT Enhancements, JAR File Format, Networking Enhancements, I/O Enhancements, Math Package, Remote Method Invocation (RMI), Object Serialization, Reflection, Java Database Connectivity (JDBC), Inner Classes, and Java Native Interface (JNI). MRJ also includes a PowerPC "just-in-time compiler" (JITc) and, for the low time, a 68040 JITc, both of which can furnish significant improvements in performance over the MRJ 1.0.2 expiration that was provided with Mac OS 8.