This includes trans- or intra-membrane regions of a protein, typically describing physicochemical properties of the secondary structure elements. For example, the location and size of the membrane spanning segments and intervening loop regions, transmembrane region IN/OUT orientation relative to the membrane, plus the following data for each amino acid: A Z-coordinate (the distance to the membrane center), the free energy of membrane insertion (calculated in a sliding window over the sequence) and a reliability score. The z-coordinate implies information about re-entrant helices, interfacial helices, the tilt of a transmembrane helix and loop lengths.