"Simplified English" is sometimes used as a generic term for a controlled language. The aerospace and defense specification started as an industry-regulated writing standard for aerospace maintenance documentation, but has become mandatory for an increasing number of military land vehicle, sea vehicle and weapons programs as well. Although it was not intended for use as a general writing standard, it has been successfully adopted by other industries and for a wide range of document types. The US government's Plain English lacks the strict vocabulary restrictions of the aerospace standard, but represents an attempt at a more general writing standard.