The writing rules
ASD-STE100 Simplified Technical English (STE) has two parts: a set of writing rules and a dictionary of approved words. This page covers the writing rules. The dictionary is covered in Controlled vocabulary.
STE has approximately 53 writing rules. The rules cover grammar and style. They make technical text shorter, clearer, and easier to read — especially for people who do not speak English as a first language.
STE is a controlled language, not the S1000D specification itself. S1000D does not force you to use STE. But many S1000D projects adopt STE through their business rules and BREX, because the two work well together: STE keeps the prose consistent, and S1000D keeps the structure consistent.
The spirit of the rules
Before the individual rules, learn the goal. Every rule serves one idea:
Write so that there is only one possible meaning.
Ambiguity is the enemy. A maintenance technician must not have to guess. The rules remove the common sources of confusion in English — long sentences, passive constructions, words with many meanings, and grammar that can be read in more than one way.
A second idea supports the first: be consistent. Use the same word for the same thing every time. Use the same structure for the same kind of step. Consistency lets the reader (and a translation system) learn your patterns quickly.
Grouped rules
The rules below are grouped by theme. The grouping is a teaching aid for this page; it is not the exact section structure of the specification.
1. Keep sentences short
Long sentences hide the action and increase the chance of error. STE sets length limits, and it sets different limits for the two kinds of text.
| Text type | Purpose | Standard maximum sentence length |
|---|---|---|
| Procedure | Tells the reader to do something (a step) | 20 words |
| Description | Explains how something works or what it is | 25 words |
Treat these numbers as the standard typical guidance from ASD-STE100. They are limits, not targets — shorter is usually better. The exact wording and any qualifications live in the official specification, which is the authority for your project.
When a sentence runs long, do not just trim words. Split it into two sentences, or move detail into a separate step.
2. Use the active voice
Write in the active voice, not the passive voice. The active voice names who does the action and puts the action up front.
| Avoid (passive) | Prefer (active) |
|---|---|
| The valve must be closed by the operator. | Close the valve. |
| The cover is removed. | Remove the cover. |
For instructions, STE uses the imperative (command) form. "Remove the cover" is shorter and clearer than "The cover should then be removed."
3. One instruction per sentence
Write only one instruction per sentence. If a step has two actions, write two sentences (or two steps).
| Avoid | Prefer |
|---|---|
| Loosen the bolt and remove the bracket. | Loosen the bolt. Remove the bracket. |
This rule makes each action easy to find, easy to check off, and easy to translate. It also pairs with the short-sentence limit: one short instruction per sentence is naturally within 20 words.
A related rule applies to descriptive text: keep to one topic per sentence. Do not mix two ideas in one sentence.
4. Use consistent terminology
Use one word for one meaning, and one meaning for one word. Pick a term for a part or an action, then use that same term everywhere.
- Do not call something a "lamp" on one page and a "light" on the next.
- Do not use "begin," "start," and "commence" for the same action — choose one approved word and keep to it.
Synonyms feel natural in everyday writing, but in technical text they make the reader wonder whether two different things are meant. The approved dictionary enforces this at the word level; the writing rules enforce it at the sentence level.
5. Avoid ambiguous -ing forms
Words that end in -ing are a common source of ambiguity in English. The same -ing word can act as a verb, a noun, or an adjective, and the reader cannot always tell which.
Consider "Removing the panel, disconnect the cable." It is unclear whether removing and disconnecting happen together or in sequence. STE restricts -ing forms so that meaning stays clear.
| Avoid | Prefer |
|---|---|
| Before removing the cover, disconnect the power. | Disconnect the power. Then remove the cover. |
When you must show order, use plain sequential sentences or numbered steps. Do not lean on -ing phrases to carry the sequence.
6. Keep grammar simple and predictable
Several rules push the same direction: prefer the simple, common form.
- Prefer simple tenses (for example, simple present and simple past) over complex ones.
- Do not leave out words that make the grammar clear. Keep articles such as "the" and "a" where they help.
- Write short paragraphs, and keep each paragraph to a single topic.
- Use clear, factual language. Avoid jargon, slang, and figures of speech.
A fast self-check: read each sentence and ask, "Could a tired reader, working in a second language, misread this?" If yes, shorten it, make it active, or split it. That single habit catches most STE violations before any tool does.
How this fits the toolchain
STE is a writing discipline, so a structural validator like the s1kd-tools toolchain does not grade your prose against all 53 rules — those tools check S1000D structure, schema conformance, and BREX rules. Checking STE itself usually needs a dedicated STE checker or a human editor. In practice, teams run both: the s1kd-tools for structure, and an STE review for language.