Modeling product characteristics is well known to software configuration management (SCM). Modeling process characteristics is relatively new to SCM. Combining process modeling and SCM enhances the current capabilities of SCM. The paper presents product and process models suitable for SCM. The outlined approach, Concert provides building blocks for developing project specific models. Concert's models are described by entity relationship diagrams. In addition, Concert uses the predicate calculus to express model restrictions. Concert offers a seamless integration of product and process modeling. The paper presents a process model for software maintenance that is based on change requests. Such a model helps SCM to recognize the course of a software project early, thus SCM need not determine the development history of a software ex post. The paper describes a tool to manage the presented models and their instances.