Tertiary structure format Textual format Trajectory format (text) XYZ The XYZ chemical file format is widely supported by many programs, although many slightly different XYZ file formats coexist (Tinker XYZ, UniChem XYZ, etc.). Basic information stored for each atom in the system are x, y and z coordinates and atom element/atomic number. 1.22 XYZ files are structured in this way: First line contains the number of atoms in the file. Second line contains a title, comment, or filename. Remaining lines contain atom information. Each line starts with the element symbol, followed by x, y and z coordinates in angstroms separated by whitespace. Multiple molecules or frames can be contained within one file, so it supports trajectory storage. XYZ files can be directly represented by a molecular viewer, as they contain all the basic information needed to build the 3D model.