When you open a CIF, DBWS/LHPM or other type of import file, ATOMS will search through it to find all the data sets or phases within it, up to a limit. If there is more than one, this dialog will present you with a list. The name of the ATOMS data file will be taken from the name of the file, and the title (Title/Axes dialog in the Input Menu) will be taken from the data set, phase or crystal selected. The extension.STR will be appended to the structure file.