Plain English helps to improve the quality of written documents. Many organizations find that its use brings commercial benefit.

Plain English consists of guidelines such as:

  • Keep your sentences short
  • Choose words appropriate for the reader
  • Use active verbs

Professional writers recognize Plain English guidelines as best practice.

However, Plain English is not sufficiently rigorous to ensure that text is unambiguous. Words such as ‘short’ and ‘appropriate’ are open to interpretation. Thousands of verbs exist in English; sometimes two or more verbs have an identical meaning, and sometimes one verb has many different meanings. A similar situation arises with nouns.

ASD Simplified Technical English

A controlled language specifies the grammatical structures and the words that a writer can use. The purpose is to create brief and unambiguous text.

ASD Simplified Technical English is one particular controlled language. The specification for the language is called ASD-STE100. The specification was developed in the aerospace industry, but it can be used in other industries.

The specification contains:

  • A dictionary of words and their meanings
  • A set of writing rules

The dictionary contains a list of words that you can use. For example, you can use ‘make sure’, but you cannot use synonyms such as ‘verify’, ‘check’, or ‘ensure’.

Generally, each word belongs to one part of speech. For example, the word ‘oil’ is specified as a noun. So:

  • ‘Oil the bearings liberally’ is not allowed, because in this context ‘oil’ is a verb
  • The oil is contaminated’ is allowed, because in this context ‘oil’ is a noun

Each word has one meaning. For example, the verb ‘to follow’ means ‘to come after’. It does not mean ‘to obey’. Instead of ‘Follow the safety instructions’, you must write ‘Obey the safety instructions’.

The rules specify the structure of the text. For example, descriptive sentences must have no more than twenty-five words. (This puts a number on the Plain English guideline to keep sentences short.)

Tenses are controlled. For example, you cannot use the present perfect tense. Typically, you would write the sentence using the simple past tense.

Each industry has its own specialist vocabulary, so ASD Simplified Technical English allows you to create a custom dictionary of approved words.

Should we be using some form of simplified English in all our technical writing? Why don’t more writers use it? What resources and software tools are available? For a discussion of issues, see

About the author

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Mike Unwalla helps people to use complex software. He has been writing user documentation for software companies since 1995.