The present invention is directed to a system and method for modifying a class file for the purpose of instrumenting without requiring separate files to correlate the instrumentation. A class file is instrumented with hooks. Each hook is injected in a method at a critical point in the code for tracking path flow, such as where the method will be entered or exited. Each hook includes an identifier to identify the method in which it is injected. Rather than using the method's name, hooks use unique major and minor codes to identify the method. Static initializers are declared for the class to output other hooks identifying the methods being instrumented. When a class is loaded, the static initializers are executed and hooks identifying the method name and the major and minor codes for each instrumented method are output to, for instance, a trace record. Then, when a method is entered or exited, the hooks identifying the entry or exit are also outputted to a trace record. When postprocessing the trace records, class and instrumentation correlation information is available for merging from trace records in the trace stream.