To realise variability at the code level, product line methods classically advocate usage of inheritance, components, frameworks, aspects or generative techniques. However, these might require unaffordable paradigm shifts for the developers if the software was not thought at the outset as a product line. Furthermore, these techniques can be conflicting with a company’s coding practices or external regulations. These concerns were the motivation for the industry-university collaboration described in this paper where we develop a minimally intrusive coding technique based on tags. It is supported by a toolchain and is now in use in the partner company for the development of flight grade satellite communication software libraries. Categories and Subject Descriptors D.2.13 [Software Engineering]: Reusable Software General Terms Design, Documentation, Languages Keywords Feature diagram, code tagging