The cosmological analysis of X-ray cluster surveys - III. 4D X-ray observable diagrams M. Pierre, A. Valotti, L. Faccioli, N. Clerc, R. Gastaud, E. Koulouridis and F. Pacaud A&A, 607 (2017) A123 Published online: 24 November 2017 DOI: 10.1051/0004-6361/201629765