ASD STE-100 Simplified Technical English, or Simplified English, is the original name of a controlled language specification originally developed for aerospace industry maintenance manuals. It is a carefully limited and standardized subset of English. It is now officially known under its trademarked name as Simplified Technical English (STE). STE is regulated for use in the aerospace and defense industries, but other industries have used it as a basis for their own controlled English standards.
Simplified Technical English is claimed to:
However, these claims come mostly from those who have invested in developing it, implementing it or supporting it. In the absence of third-party endorsement or published scientific studies, such claims should be considered unconfirmed.
The Simplified Technical English specification consists of two parts:
The Writing Rules differentiate between two types of topics: procedure and description. The Writing Rules also specify restrictions on grammar and style usage. For example, they require writers to:
The dictionary includes entries of both approved and unapproved words. The approved words can only be used according to their specified meaning. For example, the word "close" can only be used in one of two meanings:
The verb can express close a door or close a circuit, but cannot be used in other senses (for example to close the meeting or to close a business). The adjective "close" appears in the Dictionary as an unapproved word with the suggested approved alternative "near". So STE does not allow do not go close to the landing gear, but it does allow do not go near the landing gear. In addition to basic STE vocabulary listed in the Dictionary, Section 1, Words, gives explicit guidelines for adding technical names and technical verbs that writers need to describe technical information. For example, words or phrases such as overhead panel, grease, propeller, to ream, and to drill are not listed in the Dictionary, but qualify as approved terms under the guidelines in Part 1, Section 1 (specifically, Writing Rules 1.5 and 1.10).
Simplified English is sometimes used as a generic term for a controlled language. The aerospace and defense standard 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.