Shortened time-to-market cycles and increasingly complex systems are just some of the challenges faced by industry. The requirement engineering process needs to adapt to these challenges in order to guarantee that the end product fulfils the customer expectations as well as the necessary safety norms. The goal of this paper is to investigate the way engineers work in practice with the requirement engeneering processes at different stages of the development, with a particular focus on the use of requirements in cross domain development and to compare this to the existing theory in the domain.