There is currently no standard syntax for representing Java bytecodes in human-readable form. Sun's javap utility provides one representation, but its output is complicated by code offsets and constant pool index numbers. Thus, a simpler syntax of coding in Java bytecodes was created. To understand what the operands mean and their usage in programming, look at the Java Virtual Machine Specification .
Excerpts are available at the above link.
If superclassname is missing, the default java.lang.Object superclass is used. If aclass is missing, the current class is used. If aclass is missing, the current class is used. 0x indicates that the following number is in hexadecimal format. When followed by a local variable name, load and store are changed to the proper x load or x store command based on the type of the local variable.