To successfully carry out a software maintenance or reengineering task, a suitably assembled set of tools is required, which interoperate seaminglessly. To achieve this goal, an exchange format is needed that can be used to represent the facts extracted from a software system in a standardized way; serving as an output of one tool and as an input for other tools. In this paper we propose a modular schema for C++, called the Columbus Schema. The schema has been implemented in the Columbus/CAN front end framework tool and is already utilized in several usages, one of which is its representation in the GXL form.