A short definition
Simplified Technical English is defined in the specification ASD-STE100. The specification limits the words that a writer can use and gives rules for how to use them. A controlled language is different from a style guide. A style guide gives advice. A controlled language gives a defined vocabulary and grammar, so two writers who follow it produce very similar text.
STE is not a new language. Every STE sentence is correct English. A reader who has never heard of STE can read it without training. The difference is that STE removes the parts of English that cause misunderstanding: words with many meanings, long sentences, complex verb forms and unclear references.
History of STE
In the late 1970s, the European airline industry asked aircraft manufacturers to look at the readability of maintenance documents. Aircraft were sold around the world. Many mechanics read English as a second or third language, and the manuals used a very rich, varied English. The result was slow work, extra questions and a real risk of mistakes.
The European association of aerospace companies at that time (AECMA) started a project to control the English used in these documents. The project studied real maintenance texts and the problems readers had with them. In 1986, the first guide was published as "AECMA Simplified English". In 2004, AECMA merged with other associations to form ASD, and the specification became ASD-STE100.
Over the years, the standard spread beyond aircraft. Defence organisations adopted it for equipment documentation. Later, companies in machinery, automotive, rail, energy, medical devices and software started to use it, because they had the same problem: global readers, complex products and a high cost of error.
Who maintains the standard
The Simplified Technical English Maintenance Group (STEMG) maintains ASD-STE100. The group includes specialists from industry, linguistics and technical communication. It collects change requests from users, studies them and publishes new issues of the specification. The official home of the standard is asd-ste100.org.
Purpose of STE
- Safety: an instruction that has only one meaning cannot be done the wrong way because of language.
- Comprehension: non-native readers understand short sentences and common words faster.
- Consistency: many writers produce documents that look and read the same.
- Translation: consistent text is easier to translate by people and by machines.
Structure of the standard
Part 1: Writing Rules
Part 1 contains the writing rules. They are grouped by topic: words, noun clusters, verbs, sentences, procedures, descriptive writing, safety instructions and punctuation. Each rule has an explanation and examples. We give an overview of these categories, in our own words, on the Writing Rules page.
Part 2: Dictionary
Part 2 is the dictionary. It lists approved words with their part of speech and approved meaning. It also lists many unapproved words and shows an approved word or phrase to use instead. Writers can add technical names (for example, names of parts and tools) and technical verbs that fit the rules for their own field.
Issue history
The specification has been revised many times since the first guide in 1986. Each issue clarified rules, added or removed dictionary entries and responded to user feedback. The current issue is Issue 9. Always use the latest issue from the official website, because older copies may contain rules or words that have changed.
Benefits of STE
Organisations that use STE often report shorter documents, fewer reader questions and lower translation costs. Writers often say that STE helps them think more clearly about the task they describe, because it forces one action per step and one idea per sentence. Reviewers benefit because they can point to a rule, not only to personal preference.
STE also has limits. It takes training and practice to write well in STE. It is designed for procedures and descriptions, not for marketing text or literature. And a text can follow the rules but still be technically wrong, so subject-matter review is still necessary.
How to start
Download the specification from the official source, read Part 1 carefully, and practise with real texts from your own work. Our ASD STE 100 skill page gives a learning path and exercises, and the STE checker helps you find common problems.