All disk files were contiguous disk blocks, thus there was no fragmentation. A program in need of working storage could use and modify named files, but could not expand them beyond their created size. Free space started after the last named file, and might be partially occupied by a temporary file, as the assembler or a compiler might produce. If a file was to be modified, the usual process was to use codice_3 commands to delete it, which would move any subsequent files back to close the gap, and then give that name to the temporary file as the new version of the file. Rarely modified files would thus sink towards the start of the disk as new files or new versions were appended, and frequently modified files would jostle amongst each other towards the end of the disk.