The analysis of experiments performed at various magnetic field intensities pointed to an apparent magnetic-field-dependent power threshold for the emergence of ITBs in regions of weak positive magnetic shear in JET [1]. This observation motivated our search for an objective existence criterion which could possibly lead to a better understanding and quantification of the physical processes leading to the formation of ITBs. Furthermore, there is a real interest in developing some physical and practical criterion which could be used routinely to speed up the ITB identification and characterise their main features especially for database analysis, and possibly to control their dynamics in real-time. The first section introduces the criterion, its physical and experimental relevance. In section 2, we use the criterion to investigate the role of the q-profile in the ITB physics for various injected torques. Finally, in the last section, algorithms for profile control using the real-time estimate of the criterion are proposed and numerically simulated.