Modular software is often seen as a feature of  high quality software , but  that  assertion only holds true if  the modules interact as expected.  That is why DO-178C requires that both data coupling and control coupling are shown to be in accordance with requirements.   

Section 6.4.4.2.c  of the standard  requires “analysis to confirm that the requirements-based testing has exercised the data and control coupling between code components” .   This directive is designed to  ensure that design, integration, and test objectives are met.  The document outlines how m easuring control and data coupling  can be  achieved via a combination of control and data flow analysis , and how that  process can be made more efficient through the use of software tools.