Simplified Technical English

ASD-STE100 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[according to whom?] to:

  • 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
  • Improve Reliability concerns of maintenance and assembly by reducing their probability to introduce defects

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.

Specification structure

The Simplified Technical English specification consists of two parts:

  1. Writing Rules
  2. Dictionary

Writing Rules

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:

  • 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
  • Do 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 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).

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 represents an attempt at a more general writing standard.

The regulated aerospace standard was formerly called AECMA Simplified English, because AECMA originally created the standard in the 1980s. 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.

A free copy of the official ASD-STE100 Specification can be requested through the ASD-STE100 website. Over 3600 copies of Issue 6 of the specification have been distributed.

STE is mandated by several commercial and military specifications that control the style and content of maintenance documentation, most notably ASD S1000D.

See also


  This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.



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