The runtime environment (RE) for the Java Card Platform, Version 2.2.2, contains the Java Card virtual machine (VM), the Java Card Application Programming Interface (API) classes (and industry-specific extensions), and support services.
This document, the Runtime Environment Specification for the Java Card Platform, Version 2.2.2), specifies the Java Card RE functionality required by the Java Card technology. Any implementation of Java Card technology shall provide this necessary behavior and environment.