5.7.2. Periodicity of Updating

Standardization rules or directives generally govern the period after which de jure standards must be reviewed. The review determines whether a standard is still valid and its applicability should be confirmed; whether the standard is outdated and must be updated and revised; or whether the standard is obsolete and should be withdrawn and possibly replaced by a new one. ISO standards are reviewed every five years. ISO interim documents are reviewed every three years.

Because de facto standards are market-driven, they are updated on an ad hoc basis as the dominant technology evolves.