Simplified english

For other simplified forms of English, see Simple English.

Simplified English is the original name of a controlled language originally developed for aerospace industry maintenance manuals. It offers a carefully limited and standardized subset of English. It is now officially known under its trademarked name as Simplified Technical English (STE). Although STE is regulated for use in the aerospace and defense industries, other industries have used it as a basis for developing their own controlled English standards.


Proponents claim that Simplified Technical English can:

  • Reduce ambiguity
  • Improve the clarity of technical writing, especially procedural writing
  • Improve comprehension for people whose first language is not English
  • Make human translation easier, faster and more cost effective
  • Facilitate computer-assisted translation and machine translation

Specification structure

The Simplified Technical English specification consists of two Parts:

- Part 1: Writing Rules,

- Part 2: Dictionary.

Writing Rules

The Writing Rules specify restrictions on grammar and style usage. For example, they require writers to:

  • Restrict the length of noun clusters to no more than 3 words
  • Restrict sentence length to no more than 20 words (procedural sentences) or 25 words (descriptive sentences)
  • Restrict paragraphs to no more than 6 sentences (in descriptive text)
  • Avoid slang and jargon while allowing for specific terminology
  • Make instructions as specific as possible
  • Use articles such as "a/an" and "the" wherever possible
  • Use simple verb tenses (past, present, and future)
  • Use active voice
  • Not use present participles or gerunds (unless part of a Technical Name)
  • Write sequential steps as separate sentences
  • Put commands first in warnings and cautions, with the exception of conditions


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:

  1. To move together, or to move to a position that stops or prevents materials from going in or out.
  2. To operate a circuit breaker to make an electrical circuit.

The verb can be used to express "close a door" or "close a circuit", but it 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 the 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 such as "overhead panel", "grease", "propeller", "to ream", and "to drill" are not listed in the Dictionary, but they qualify as approved terms under the guidelines listed in Part 1, Section 1 (specifically, Writing Rules 1.5 and 1.10).

Aerospace and defense standard

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[1] lacks the strict vocabulary restrictions of the aerospace standard, but it represents an attempt at a more general writing standard.

The regulated aerospace standard was formerly called AECMA Simplified English, because AECMA (a French acronym for the Association Européenne des Constructeurs de Matériel aérospatial, in English the European Association of Aerospace Manufacturers) originally created the standard in the 1980s. The AECMA standard originally came from Fokker, which had based their standard on earlier controlled languages, especially Caterpillar Fundamental English. In 2005, AECMA was subsumed by the Aerospace and Defence Industries Association of Europe (ASD), which renamed its standard to ASD Simplified Technical English or STE. STE is defined by the specification ASD-STE100, which is maintained by the Simplified Technical English Maintenance Group (STEMG).[2] The specification contains a set of restrictions on the grammar and style of procedural and descriptive text. It also contains a dictionary of approx. 875 approved general words. Writers are given guidelines for adding technical names and technical verbs to their documentation. STE is mandated by several commercial and military specifications that control the style and content of maintenance documentation, most notably ASD S1000D.

See also

Constructed languages portal


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