Wrapper class for 'compound' operations, virtual instructions that don't exist as byte code, but give a useful meaning. For example, the (virtual) PUSH instruction takes an arbitrary argument and produces the appropriate code at dump time (ICONST, LDC, BIPUSH, ...). Also you can use the SWITCH instruction as a useful template for either LOOKUPSWITCH or TABLESWITCH. The interface provides the possibility for the user to write 'templates' or 'macros' for such reusable code patterns.