Requirements Engineering (RE) is an important activity in system engineering and produces, from the users' needs, specifications related to what the final system must be. This process in complex systems engineering is extremely intense, because there is a large number of stakeholders involved, with expertise deriving from heterogeneous domains. Moreover, requirements' improvements and variations are common during system life cycle phases. Thus, there is a risk of inconsistency of requirements during the engineering of a system. This paper provides a contribution in requirements engineering as it explores requirements interoperability in complex systems when multiples dimensions are involved. It discusses requirement management according to the cross-domains dimension, the cross-systems life cycle dimension, the cross-requirements dimension and the risk of inconsistency when three dimensions are involved simultaneously during the life cycle phases. The main result is an overview of the existing gaps in one and/or more dimensions allowing a discussion on the possibilities to cope with the problem of requirements inconsistency in multiples dimensions.