The 53 rules, by section.
ASD-STE100 organises its writing rules into nine sections, from individual word choice through to punctuation and word count. Filter by section, or by whether a rule can be checked automatically.
The nine sections run in the order the standard sets them. Section 1 covers word choice and technical nouns, and is the largest at 14 rules. Section 2 covers multi-word nouns, section 3 verbs, where the standard is at its most restrictive, and section 4 sentence construction. Sections 5, 6 and 7 each apply to a particular kind of writing: procedures, descriptive text, and safety instructions. Section 8 covers punctuation and the rules for counting words, which exist so that the length limits are testable rather than arguable. Section 9 covers writing practices that apply throughout.
Each rule has its own page, carrying the rule in plain terms, what a checker looks for, how to rewrite what it finds, worked examples, and the page of the standard it comes from. Seven of the 53 are marked as needing human judgement: a checker can raise candidates on them and cannot decide them. The examples are ours rather than the standard's, because this site publishes commentary on ASD-STE100 and does not reproduce it.
53 of 53 rules shown.
1. Words (14)
Use approved words only
Every word in the text must be either an approved word from the STE dictionary, a technical noun that fits one of the 22 approved technical-noun categories (rule 1.5), or a technical verb that fits one of the 4 approved technical-verb categories (rule 1.12).
Use approved words as the specified part of speech
Use an approved dictionary word only as the part of speech (noun, verb, adjective, etc.) that the dictionary specifies for it; do not convert it to a different part of speech.
Use approved words with their approved meanings only
Use each approved dictionary word only with the approved meaning or meanings the STE dictionary assigns it, even where standard English allows broader or different meanings. Some approved words have more than one approved meaning; use any of those, but never a standard-English sense the dictionary does not list.
Use only the approved forms of verbs and adjectives
Use each approved verb only in the specific forms the dictionary lists for it (typically infinitive/imperative, simple present, simple past, and past participle — e.g. REMOVE, REMOVES, REMOVED, REMOVED) and each approved adjective only in its dictionary-given base, comparative, and superlative forms (e.g. SLOW, SLOWER, SLOWEST). Adjectives that regularly form comparatives/superlatives with 'more'/'most' are not given separate dictionary forms, since 'more' and 'most' are themselves approved words — except where a more specific rule (e.g. rule 1.5, category 17 colors) bans comparison for that word outright.
You can use technical nouns from approved categories
A word not in the STE dictionary may be used as a technical noun only if it fits one of the 22 approved technical-noun categories listed in technicalNounCategories (each with its official definition, examples, and source page). Category membership does not by itself override the requirement to use the approved company/industry/subject-field term when one exists (rule 1.8). For category 17 (colors): colors are technical nouns even though they behave grammatically as adjectives, and comparative or superlative color forms (e.g. 'blacker', 'the reddest') are never permitted in STE — there is no compliant 'more'/'most' workaround for a color comparison.
Use non-approved words only as technical nouns
A word may be used as a technical noun (or as part of one) — never with its ordinary, non-technical meaning — in two cases: (a) the dictionary explicitly marks it not approved, or (b) the word is absent from the dictionary entirely. Both cases require a genuine, valid technical-noun use under rule 1.5.
Do not use technical nouns as verbs
Use a technical noun only as a noun (or as an adjective inside a different technical noun) — never convert it into a verb.
Use only approved technical nouns
When your company, industry, or subject field has an approved technical noun for something, use that exact term rather than an invented, generic, or overly obscure alternative.
Use short and easy to understand technical nouns
When no technical noun is approved in your company, industry, or subject field, select one that is short (not more than three words) and easy to understand, relying on illustrations or index numbers for extra specificity rather than a long descriptive noun phrase.
Do not use regional, slang, or jargon words as technical nouns
Do not use technical nouns that are only understood by people in a specific region, or that are slang or narrow jargon understood by only a small group — always use well-known, widely understood terms.
Use the same technical noun for the same item throughout
Once you select the approved technical noun for an item, use that exact same term every time you refer to that item in the text — never switch to a synonym or a different technical noun for it.
You can use technical verbs from approved categories
A word not in the STE dictionary may be used as a technical verb only if it fits one of the 4 approved technical-verb categories listed in technicalVerbCategories (each with its official definition, subcategories, examples, and source page) — and only when no approved dictionary verb already expresses the same instruction clearly.
Do not use technical verbs as nouns
Use a technical verb only as a verb — never convert it into a noun. Its past-participle form may still be used as an adjective.
Use American English spelling
Use American English spelling as given in the STE dictionary, unless an applicable official directive specifically requires a different spelling; leave quoted text (e.g. text shown on a screen or label) unchanged even if it uses non-American spelling.
2. Multi-word nouns (2)
Write multi-word nouns of no more than three words
A multi-word noun is a string of nouns and/or adjectives (with no article or preposition breaking it up) that together modify a head noun and function as one part of speech. Keep every multi-word noun to a maximum of three words; if a concept needs more, restructure the phrase (for example with prepositions such as 'of,' 'on,' 'in,' or 'for') instead of stacking more than three words together.
Write long technical nouns in full, then shorten or hyphenate them
When an approved technical noun (from official company, engineering, or parts-catalog documentation) itself has more than three words and cannot be shortened in meaning, write it out in full the first time it occurs in the text. After that first occurrence, if possible, you can either (a) switch to a shorter form or an approved abbreviation for the rest of the document, or (b) use hyphens between words that function together as one unit so the phrase reads as three words or fewer. Abbreviating or hyphenating is not necessary for an approved technical noun that already has three words or fewer, and you must never alter hyphens or abbreviations that are already fixed parts of an official approved technical noun.
3. Verbs (7)
Use only the verb forms that are given in the dictionary
For each approved verb, use only the specific inflected forms listed for it in the STE dictionary (typically the base/infinitive, the simple present, the simple past, and the past participle). Do not use, invent, or regularize any form of an approved verb that is not one of the forms the dictionary gives for it, even if that form would be grammatically valid in general English.
Use only approved verb forms and tenses
Use verbs only in one of these forms or tenses: the infinitive form, the imperative (command) form, the simple present tense, the simple past tense, the simple future tense, or the past participle used as an adjective. Do not use other tenses or constructions such as the present/past perfect, the present/past progressive, or any other complex (multi-auxiliary) verb construction.
Use the past participle form as an adjective
A verb's past participle form may be used as an adjective — either directly before the noun it modifies, or after a form of 'to be,' 'to become,' or 'to stay' — to show the condition of something; this is not passive voice. Only use a past participle as an adjective if it (or its adjective sense) is listed in the dictionary, including approved adjectives such as 'permitted' or 'damaged' whose underlying verb is not itself approved.
Do not use auxiliary verbs to make complex verb constructions
Do not build complex verb constructions with auxiliary verbs used as the main verb of a perfect tense or a passive/modal construction — for example 'have/has' plus a past participle to form a perfect tense, or 'is/are/can/must/will' plus a past participle to form a modal or passive construction where the participle functions as the action verb, not as an adjective. This does not cover a past participle used purely as an adjective (rule 3.3) or the narrow permitted descriptive passive with a genuinely unknown agent (rule 3.6) — those are separate, permitted constructions that happen to share the same surface 'be + past participle' form. These disallowed constructions produce non-approved tenses and passive-voice sentences. Instead, identify the true agent of the action and use it as the subject of an approved simple tense (see rule 3.2), or use the imperative for procedural instructions.
Use the "-ing" form of a verb only as a technical noun or noun modifier
Do not use a word with an '-ing' form as part of a verb phrase (a progressive tense) or to build long modifying clauses attached to a noun. The '-ing' form may be used in two separate, independent ways: (1) as a valid technical noun (for example in a procedure title or heading) or as a functional modifier within a technical noun describing the function of a system, component, part, tool, or material — this path does not require the specific '-ing' word to also appear in the small dictionary-approved general list; or (2) as one of the small number of dictionary-approved general '-ing' words. A word only needs to satisfy one of these two paths, not both.
Use the active voice
Always write in the active voice, where the grammatical subject performs the action of the sentence. In descriptive writing only, the passive voice is permitted when the agent (the person or thing that does the action) is genuinely unknown; procedural (instructional) writing must always use the active voice.
Use an approved verb to describe an action, not a noun or other part of speech
When an approved verb exists that describes the action you mean, use that verb directly rather than a nominalized construction (e.g. 'give an indication of,' 'before the removal of') or another part of speech. If a word is not approved as a verb in the dictionary, do not use it as a verb — restructure the sentence instead, for example with a 'do a/an <noun> of' construction.
4. Sentences (5)
Write short and clear sentences
Write short sentences with clear structure that give accurate instructions and information. In procedures, give instructions directly to the reader in the imperative form; in descriptive text, give each sentence only one topic and build up information gradually across the sentences that follow, and never write abstract statements that omit the accuracy the reader needs.
Do not omit words or use contractions to shorten sentences
Write every sentence with all of its parts — do not omit nouns, verbs, subjects, or articles to make the sentence shorter, and do not use contractions such as "don't" or "isn't". Omitted words and contractions make a sentence shorter but not easier to read, and can create ambiguity.
Use a vertical list for complex text
When a sentence would otherwise be long because it includes many items (such as parts, components, or documents) or many actions, present those items as a vertical list instead. Introduce the list with a colon, mark each item consistently (dash, bullet, letter, or number), start each item with an uppercase letter, and punctuate the items according to whether each is a full sentence.
Use connecting words and phrases to link related sentences
Use an approved connecting word (such as "and", "but", "then", "thus"), an approved connecting phrase (such as "as a result", "at the same time"), or a demonstrative adjective to link a sentence to the related idea in the sentence before it, giving descriptive text a logical structure and clarifying explanations that follow a work step or a safety instruction.
Use an article or demonstrative adjective before a noun
When applicable, use an article (the, a, an) or a demonstrative adjective (this, these) before a noun or multi-word noun to show its position in the sentence; do not omit it to shorten the text. Do not use an article before a noun in a general statement or abstract concept, and do not use a definite article before a noun that is followed by an alphanumeric identifier, since the identifier makes it a proper noun.
5. Procedural writing (5)
Write short sentences with a maximum of 20 words
In procedural writing, including warnings, cautions, and other safety instructions, write short sentences with a maximum of 20 words each. If a sentence is longer than 20 words, split it into two or more shorter sentences rather than leaving it as one long sentence.
Write only one instruction per sentence unless actions are simultaneous
Write only one instruction in each sentence of a procedure, and clearly show the sequence of work steps, usually with numbers or letters. Write more than one instruction in a single sentence only when the actions occur at the same time; you may also write more than one sentence within a single work step when the actions are simultaneous or when a result or limit follows immediately after the action.
Write instructions in the imperative form
Write every instruction in a procedure using the imperative (command) verb form, addressed directly to the reader, rather than passive voice or a statement about capability or permission. Do not use "must" immediately before the imperative form unless the instruction is safety-critical or states an important condition.
State a leading condition as a descriptive statement, separated by a comma
When a work step depends on a condition the reader must know about first, start the instruction with a descriptive statement of that condition, then divide the condition from the command with a comma, placing the imperative instruction after the comma.
Write notes only to give information, not instructions
A note must give only descriptive information to help the reader during a procedure — never an instruction, requirement, or limit. Do not use the imperative form in a note, and do not use a note to state a result, tolerance, or limit that belongs directly in the related work step; each sentence in a note may have up to 25 words.
6. Descriptive writing (6)
Give information gradually
In descriptive text, present information gradually and make sure each sentence contains only one subject. Do not pack multiple facts or ideas about different subjects into one sentence, since this forces the reader to re-read the text to understand it.
Use key words and key phrases to give your text a logical structure
Use key words and key phrases — the same terminology repeated exactly — to connect a sentence to the ideas introduced earlier in the paragraph (not necessarily only the immediately preceding sentence), and use approved connecting words or phrases (for example, "and," "but," "then," "thus," "as a result," "at the same time") as one method, among others, to signal how a sentence relates to an earlier one. This gives the text a logical, easy-to-follow structure.
Write short sentences — maximum 25 words in descriptive text
In descriptive writing, use a maximum of 25 words per sentence. Descriptive text is permitted a higher word count than procedural text because its subject matter is inherently more complex, but any sentence over the limit must still be split into shorter sentences.
Use paragraphs to show related information
Structure descriptive text into paragraphs, where each paragraph opens with a topic sentence that states what the paragraph is about, and every following sentence explains or adds information related to that topic. A new paragraph signals to the reader that a new or different topic follows.
Make sure that each paragraph has only one topic
Each paragraph in descriptive text must cover exactly one topic. The topic sentence — usually containing a key word and/or a connecting word or phrase — states that topic, and every other sentence in the paragraph must relate to it; do not combine two or more distinct topics in the same paragraph.
No paragraph may have more than six sentences
Limit each paragraph in descriptive text to a maximum of six sentences. If a paragraph would require more than six sentences, divide it into two or more smaller paragraphs, each covering a distinct part of the topic.
7. Safety instructions (3)
Use an applicable word to identify the level of risk
Immediately identify the level of risk in a safety instruction with an applicable signal word (or symbol) — use "warning" when there is a risk of injury or death, and "caution" when there is only a risk of damage to objects, tools, or equipment. If both a warning-level and a caution-level risk are present together, label the instruction as a "warning."
Start a safety instruction with a clear and accurate command or condition
Begin a safety instruction with a clear, accurate command telling the reader what to do or not do; if the reader needs to know a condition before starting the procedure or work step, begin with that condition instead. Either way, the actionable part must come first so the reader immediately knows how to prevent an accident.
Give an explanation to show the risk or possible result
If it is possible, after the command or condition in a safety instruction (rule 7.2), give an explanation that clearly states the specific risk or possible result if the reader does not obey it. A concrete, specified risk helps the reader understand why the precaution matters and makes them more likely to follow it. The explanation is conditional on it being possible to state — not every WARNING or CAUTION is automatically non-STE for omitting one.
8. Punctuation and word count (7)
Do not use the semicolon
You can use all standard English punctuation marks except the semicolon (;). Where a semicolon would normally join two related independent clauses, write two separate sentences instead.
Use hyphens to connect words that are directly related
Use a hyphen (-) to connect two or more words that are directly related, including multi-word adjectives before a noun, two-word numbers or fractions, letter/number-plus-noun shape terms, noun-derived compound verbs, and prefixes ending in a vowel joined to a root word starting with a vowel.
Use parentheses only for these seven approved purposes
Use parentheses only to: reference an illustration or other text; give a letter or number identifying an item on an illustration or in text; identify a work-step number in a procedure; show an abbreviation; give the singular and plural forms of a noun together; explain a word or part of a sentence; or present an alternative.
In a vertical list, a colon has the effect of a period on word count
When a colon introduces a vertical list, it acts like a period: the lead-in text before the colon must not exceed the applicable sentence word-count limit (20 words for a procedural sentence, 25 words for a descriptive sentence), and each item after the colon is counted as a new, independent sentence subject to that same limit.
Text in parentheses counts as one word
When counting words for a sentence's word-count limit, count an entire parenthetical remark as exactly one word of that sentence, regardless of how many words it actually contains. The words inside the parentheses are also counted separately as their own independent sentence against its own limit. A parenthetical identifier (a number, a letter, an alphanumeric identifier, or an abbreviation) likewise counts as one word.
Count numbers, units, abbreviations, identifiers, quoted text, titles, and proper nouns as one word each
When counting words for a sentence's word-count limit, count each of the following as a single word: a standalone number; a number together with its unit of measurement; an abbreviation, acronym, or initialism; an alphanumeric identifier; a block of quoted text (including text distinguished by uppercase or a different font to show quotation); a title, heading, or text reproduced from a placard or label; and a proper noun naming an individual, group, organization, or geopolitical entity. Numbers that are only paragraph or work-step numbering are not counted at all.
Hyphenated words count as one word
A hyphenated group of words that functions as a single adjective before a noun, or as a compound technical noun built for clarity, counts as one word when counting sentence length — even though it is made of multiple hyphen-joined components.
9. Writing practices (4)
Use a different sentence construction when a word-for-word replacement is not enough
When a non-approved word cannot simply be swapped for an approved word with the same part of speech and the same meaning, do not force a literal word-for-word replacement. Instead, restructure the whole sentence using approved words so it preserves the original meaning clearly and grammatically.
Use each approved word only with its approved meaning and approved part of speech
Many STE-approved words carry only one approved meaning and/or one approved part of speech, which can be narrower than their meanings in standard English. Always use an approved word only in the sense and grammatical role the dictionary assigns it, never in another standard-English sense or part of speech it happens to also have.
Do not combine approved words into phrasal verbs
Do not combine an approved verb with a preposition or particle to form a phrasal verb whose combined meaning differs from the individual approved meanings of its parts (e.g. 'put out' meaning 'extinguish'). Use the single approved word that expresses the intended meaning instead. A small number of phrasal verbs with a restricted approved meaning (e.g. 'put on', 'come on') are dictionary exceptions and remain permitted.
Use consistent terminology and wording for the same item and the same type of work step
Once you choose a technical noun for an item, or a sentence style/wording for a recurring type of instruction, use that exact same term and wording every time that item or instruction type occurs in the text, rather than varying the phrasing for the sake of variety.