Hello list! I've just filed a bug report about the use of prefixes in wget [1]. I write this email to start discussion about the topic.
I think it's important to use binary prefixes just to make things clear and unambigous. Right now the notation 10MB can be read at least like: - The informatic-centric guy will read 10 * 2^20 Bytes - The standard-centric guy will read 10 * 10^6 Bytes - The agnostic-centric (or just any other one) won't be sure about what it means (10^6 or 2^20???) Since IEC [2], IEEE [3], the US National Institute of Science and Technology [4], the European Committee for Electrotechnical Standardization (CENELEC) as the harmonization document HD 60027-2:2003-03 [5] that will be adopted as a European standard [6] has proposed some new prefixes for binary multipliers (kibi (Ki) for 2^10, mebi (Mi) for 2^20, ...) it'll be a good idea to use them where it's needed. I know that kibibyte must sound weird, but if people start using it, maybe in the next few years everybody will get used to it, and there will be no more discussions because everybody will be used to read 500 GiB as 500 * 2^30 bytes, and 500GB as 500 * 10^9 bytes. And the way to make it happen is start using both prefixes in its correct use from now on. The SI (International System of Units) [7] also promotes the use of this new binary prefixes. From the right margin [8]: "These SI prefixes refer strictly to powers of 10. They should not be used to indicate powers of 2 (for example, one kilobit represents 1000 bits and not 1024 bits). The IEC has adopted prefixes for binary powers in the international standard IEC 60027-2: 2005, third edition, Letter symbols to be used in electrical technology – Part 2: Telecommunications and electronics. The names and symbols for the prefixes corresponding to 2^10, 2^20, 2^30, 2^40, 2^50, and 2^60 are, respectively: kibi, Ki; mebi, Mi; gibi, Gi; tebi, Ti; pebi, Pi; and exbi, Ei. Thus, for example, one kibibyte would be written: 1 KiB = 2^10 B = 1024 B, where B denotes a byte. Although these prefixes are not part of the SI, they should be used in the field of information technology to avoid the incorrect usage of the SI prefixes." It's also important to note that the new ISO/IEC 80000 [9] is also adding the new binary prefixes. [1] http://savannah.gnu.org/bugs/index.php?23713 [2] http://www.iec.ch/zone/si/si_bytes.htm [3] http://en.wikipedia.org/wiki/IEEE_1541 [4] http://physics.nist.gov/cuu/Units/binary.html [5] http://tcelis.cenelec.be/pls/portal30/CELISPROC.RPT_WEB_PROJECT_D.SHOW?p_arg_names=project_number&p_arg_values=15306 [6] http://tcelis.cenelec.be/pls/portal30/CELISPROC.RPT_WEB_PROJECT_D.SHOW?p_arg_names=project_number&p_arg_values=20776 [7] http://en.wikipedia.org/wiki/SI [8] http://www.bipm.org/en/si/si_brochure/chapter3/prefixes.html [9] http://en.wikipedia.org/wiki/ISO/IEC_80000
