A Java compiler is a compiler for the Java programming language. Some Java compilers output optimized machine code for a particular hardware/operating system combination, called a domain specific computer system. An example would be the now discontinued GNU Compiler for Java. The most common form of output from a Java compiler is Java class files containing cross-platform intermediate representation (IR), called Java bytecode. The Java virtual machine (JVM) loads the class files and either interprets the bytecode or just-in-time compiles it to machine code and then possibly optimizes it using dynamic compilation. A standard on how to interact with Java compilers was specified in JSR 199.