Rhino was released to Mozilla Foundation in April 1998. Originally Rhino classfile generation had been held back from release. However the licensors of Rhino have now agreed to release all of Rhino to open source, including class file generation. Since its release to open source, Rhino has found a variety of uses and an increasing number of people have contributed to the code. The project gets its name from the animal on the cover of the JavaScript book from O'Reilly Media. As of version 1.7R11 (May 2019), Rhino supports Java 8 and up, and supports a number of ECMAScript ES6/ES2015 features.