Simplified Technical English


English to ASD-STE100

Have your US or UK English documents converted to Simplified Technical English.


German or Greek to ASD-STE100

Have your German or Greek documents translated into Simplified Technical English.


ASD-STE100 training

Training sessions for individuals or groups on how to use the ASD-STE100 Specification.

What is Simplified Technical English?

English is the language most frequently used for writing technical documentation. However, it is often not the native language of the readers nor the authors of such documentation. As a result, the complex sentence structures and the range of meanings and synonyms of English words can cause confusion.

Complex technical instructions can be misunderstood, and misunderstandings can lead to accidents. Simplified Technical English makes technical texts easy to understand for all readers.

Simplified Technical English is a controlled language developed in the early Eighties to help users of maintenance documentation written in English understand what they read. It was initially targeted at commercial aviation but later became a requirement for defense projects. Today, other industries use Simplified Technical English beyond its original intended purpose of maintenance documentation, and outside the aerospace and defense industry.

Other indicative sectors using the Simplified Technical English ASD-STE100 Specification are:

  • Energy (e.g., solar, oil, gas, nuclear)
  • Financial institutions (e.g., banks)
  • Industrial machinery (e.g., manufacturing)
  • Information technology (e.g., software, hardware, high-tech)
  • Linguistic services (e.g., translation, technical writing)
  • Medical and healthcare (e.g., medical devices)
  • Transportation (e.g., aerospace, airlines, shipping, railways)

The current issue of the ASD-STE100 Specification is dated April 2021 (Issue 8). Issue 9 of the Specification is expected to launch in 2025. Although the structure of the Specification is stable and consolidated, the language has to keep abreast of the evolution of technology, and amended on the basis of continuous and indispensable user feedback.

You may request a free copy of the ASD-STE100 Specification from the official ASD-STE100 website or use the form at the end of this page.

What is the structure of the ASD-STE100 Specification?

The ASD-STE100 Specification provides a set of Writing Rules and a Dictionary of controlled vocabulary. The Writing Rules cover grammar and style; the Dictionary specifies the words you can use.

Writing rules

The writing rules differentiate between procedural and descriptive writing and cover aspects of grammar and style. A non-exhaustive list of the writing rules includes the following:

  • Use the Dictionary’s words only according to the approved part of speech and meaning.
  • Make instructions as clear and specific as possible.
  • Noun clusters should not have more than three words.
  • Use the approved verb to make only the infinitive, imperative, simple present and simple past, past participle (only as an adjective), and future tense.
  • Do not use auxiliary verbs for complex verb structures.
  • Use a verb’s “-ing” form only as a technical name or modifier in a technical name.
  • Do not use passive voice.
  • Write short sentences of up to 20 words in instructions (procedures) and 25 words in descriptive texts.
  • To shorten your text, do not omit parts of the sentence (e.g., verb, subject, article).
  • Use vertical lists for complex text.
  • Write one instruction per sentence.
  • Write only one topic per paragraph.
  • Do not write more than 6 sentences per paragraph.
  • Start safety instructions with a clear command or condition.


These words have been chosen for their simplicity and ease of recognition. In general, there is only one word for one meaning and one part of speech for one word. If there are several words in English for a specific thing or action (synonyms), this Specification selects one of these synonyms and excludes all others (“one word – one meaning”). For example, “start” has been chosen instead of “begin”, “commence”, “initiate”, or “originate”. The American version is used if there is a choice between American and British English words and spelling.

In addition to the Dictionary, the ASD-STE100 Specification allows company-specific, industry-specific or product-specific technical words, known as technical names and technical verbs. Writers can use the Dictionary’s approved words as a core vocabulary and any technical names and technical verbs.

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Note: ASD-STE100 Simplified Technical English is a copyright and a trademark of ASD, Brussels, Belgium.

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Note:  If you do not want to provide personal or company details, please indicate “PERSONAL USE” instead of your name, but always give information on COUNTRY, FIELD OF ACTIVITY, and ASD-STE100 USER.

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