 A single file format, such as 7z, can support multiple different compression algorithms including LZMA, LZMA2, PPMd and BZip2.For a decompression utility to correctly expand an archive of either the self-extracting or standard variety, it must be able to operate on both the file format and algorithm used.The exact executable code placed at the beginning of a self-extracting archive may therefore need to be varied depending on what options were used to create the archive.