In IEC 80000-13:2008, names, symbols and definitions for quantities and units used in information science and technology are given. Where appropriate, conversion factors are also given. International Standard IEC 80000-13 has been prepared by IEC technical committee 25: Quantities and units, and their letter symbols in co-operation with ISO/TC 12. This standard cancels and replaces subclauses 3.8 and 3.9 of IEC 60027-2:2005. The only significant change is the addition of explicit definitions for some quantities.