What is “mutual binary” compatibility mode?
The signature test binary compatibility check mode verifies that a Java technology implementation undergoing compatibility testing and its referenced APIs are mutually binary compatible as defined in Chapter 13, “Binary Compatibility,” of The Java Language Specification. This assures that any application runs with any compatible API without any linkage errors. This check is less strict than the default source compatibility check. It is for use primarily in the special case of when a technology is developed for Java technology environments that are purely runtime. Such an environment does not provide a Java technology-based compiler (Java compiler), nor does it include class files that could be used to compile applications for that environment. Because of the limited use of such an environment, the API requirements are slightly relaxed compared to environments that support application development.