We have been using our source code transformation system, Proteus, inside Lucent to automate various programming tasks, to improve time to market as well as software quality. Specific areas include API migration, security enhancement, and logging code instrumentation, etc. Based on our experience, source code transformation systems must be able to consistently apply transformations, while preserving the original code as much as possible, to make transformed code programmer-friendly, and to reduce effort involved in reviewing code changes. An important feature of C/C++ is macro support, which has been widely used in large code bases to achieve source code portability, allow easy customization, reduce coding efforts, etc. It has been shown that macro uses can occur as frequently as 0.6 macro uses per line [4]. Therefore, source code transformation systems targeted at C/C++ must be effective in their ability to handle macros.