Simple English: Write Like an Aerospace Manual

Write technical text with the rules of ASD-STE100 Simplified Technical English. STE is the controlled language that aerospace and defense manufacturers use for maintenance documentation. The rules exist so that a tired reader who is not a native English speaker cannot misread an instruction. They remove the usual signs of AI-generated text as a side effect: long sentences, synonym rotation, hedges, filler, and decorative clauses.

Write for that tired reader. Each sentence must survive one read.

Your Task

When asked to write or rewrite technical text:

1. Select the mode (pragmatic or strict, below).
2. Classify each passage as procedural or descriptive. Every other rule depends on this.
3. Correct your vocabulary before drafting. In strict mode, use make sure that for the check/verify/confirm/ensure concept — the dictionary rejects all four as verbs. In pragmatic mode, pick one and keep it. Pick ONE noun for config/settings (all are valid technical nouns — pick one and keep it). Use no other word for these concepts in the whole document.
4. Apply the rules from the catalog below.
5. Do the self-check before you deliver. This step is not optional.
6. Never touch code, identifiers, commands, or quoted errors (see Untouchables).

When asked to CHECK text instead of writing it, report each violation as: rule number, the offending text, a compliant rewrite. Cite only rule numbers that exist in this file. Do not cite rule numbers from memory: the numbering is unintuitive and models invent it (tested — an agent without this file cited "Rule 3.1: short sentences"; the real Rule 3.1 is about verb forms).

Two Modes

Step 1: Classify the Text

Do not mix the two in one passage. A "Getting started" section is procedural. An "Architecture" section is descriptive. A note inside a procedure is descriptive (25-word limit, no imperative).

THE RULE CATALOG

53 rules in 9 sections, paraphrased from ASD-STE100 Issue 9 with software examples. The official wording is in the free standard at asd-ste100.org.

Section 1 — Words (Rules 1.1-1.14)

In pragmatic mode, rules 1.5, 1.8, and 1.12 do the heavy lifting: your domain vocabulary is legal. The ones agents break are 1.7, 1.11, and 1.13.

Before: You can webhook the event, then do a deploy. After: Send the event to the webhook. Then deploy the service.

Section 2 — Multi-word nouns (Rules 2.1-2.2)

Break long noun chains with prepositions (of, on, in, for):

Before: the connection pool timeout configuration value After: the timeout value for the connection pool

Section 3 — Verbs (Rules 3.1-3.7)

Approved modals: can, will, must. Banned: should, would, may, might, could. The standard rejects "could" even for possibility: write "an explosion can occur", never "could occur". For "should": a requirement becomes "must"; a suggestion is stated as fact or deleted. This matters double for agent instructions — models read "should" as optional.

Before: The migration has completed and the table is being rebuilt. After: The migration is complete. The database rebuilds the table.

Before: The flag can be set in the config file, making restarts unnecessary. After: You can set the flag in the config file. Then a restart is not necessary.

Before: The temperature must be adjusted. After: Adjust the temperature.

Section 4 — Sentences (Rules 4.1-4.5)

Rule 4.2 is the anti-terseness rule. STE is short sentences with complete grammar, not telegraph style:

Wrong shortening: Ensure file exists before running. STE: Make sure that the file exists before you run the command.

Section 5 — Procedural writing (Rules 5.1-5.5)

Before: You'll want to grab the API key from the dashboard before configuring the client, which you can do under Settings. After: Get the API key from the dashboard, under Settings. Then configure the client with this key.

Section 6 — Descriptive writing (Rules 6.1-6.6)

No imperative in descriptive text. Descriptions explain; procedures instruct.

Section 7 — Safety instructions (Rules 7.1-7.3)

Never bury the instruction after the explanation. The pattern transfers directly to destructive CLI flags, irreversible migrations, and dangerous API options.

Before: Note that data loss may occur in some circumstances if the destructive flag happens to be enabled when running against production. After: CAUTION: Do not use the --force flag against production. The flag deletes rows that do not match the source.

Section 8 — Punctuation and word count (Rules 8.1-8.7)

Rule 8.6 matters for software text: sqlpipe run --config sqlpipe.yaml in backticks is quoted text and counts as one word. Long identifiers do not blow your sentence budget.

Section 9 — Writing practices (Rules 9.1-9.4, GR-1 to GR-8)

General recommendations GR-1 to GR-8: keep the conjunction "that", be careful with "with", give pronouns clear referents, prefer "this + noun" over bare "this", avoid false friends, avoid Latin abbreviations, use inclusive language, and use the possessive apostrophe form only when you are sure it is correct (GR-8: if unsure, do not use it — non-native readers find it hard).

GR-6 for software docs: "e.g." → "for example", "i.e." → "that is", and delete "etc." — name the items or write "and more".

VOCABULARY DISCIPLINE

The official dictionary (~900 approved words, ~1,200 banned words with alternatives) is copyrighted by ASD and is not reproduced here. Its mechanics apply without it: one word, one meaning, one part of speech.

Known part-of-speech rulings, useful as patterns:

The modal ladder

Slop-to-simple substitutions

This table is ours, not the ASD dictionary. It maps the words AI-generated docs overuse to plain replacements. If the word carries no fact, delete it instead of replacing it.

Consistency pass

Collapse synonym rotations to one term each (Rules 1.11, 9.4). The two lists below work differently.

Technical nouns — not in the dictionary. Pick one and keep it consistent (both modes):

• config / configuration / settings / options → pick one

Dictionary rulings — the standard has already chosen. Use the approved word (strict mode); pick one and keep it consistent (pragmatic mode):

Untouchables

These are technical names (Rules 1.5, 8.6). Leave them exact, even when they break vocabulary rules:

• Code blocks, inline code, identifiers, CLI commands, flags, file paths
• Quoted error messages and log lines
• Product names, API endpoint names, config keys
• Numbers with units — each counts as one word in the sentence limit

Beyond Documentation

Same rules, different targets. Full adaptations in references/use-cases.md:

• Error messages: state what happened (simple past), the cause if known, then the fix as an imperative. No "Oops", no "Please ensure", no apology filler.
• Runbooks: STE's home turf. Imperative steps, conditions first, warnings before the step.
• Incident reports: simple past only. "We have identified an issue that may have impacted" becomes "Between 14:02 and 14:31 UTC, 12% of requests failed."
• Release notes: breaking changes follow the warning pattern — command first, risk second.
• Agent instructions (prompts, AGENTS.md): a system prompt is a procedure for a reader that cannot ask questions. One instruction per sentence, no "should", condition first.
• Translation prep: STE's original job. One meaning per word plus complete grammar removes most translation ambiguity.

Self-Check Before You Deliver

This step is not optional. Run these four checks on your draft:

1. Count words in your three longest sentences. Over the 20/25 limit → split them.
2. Search your draft for: 'll, 're, 's (contraction), has been, have been, should, -ing verbs after a comma, semicolons.
3. Search for every if and when. Each one stands at the START of its sentence, before the command. "Increase the timeout if the network is slow" → "If the network is slow, increase the timeout."
4. Search for the verbs you did NOT pick in Your Task step 3 (the check/verify/confirm set). Replace every hit with your chosen verb.

Fix what you find, then deliver. For a full audit, run references/checklist.md.

Full Example

Before (real unedited AI output):

Connection timeouts. If sqlpipe hangs or fails with dial tcp: i/o timeout, check that the host running sqlpipe can reach the Postgres port (usually 5432) — this is often a security group or firewall rule blocking the connection. If you're connecting to a managed database (RDS, Cloud SQL, etc.), confirm the instance allows connections from sqlpipe's IP. You can also try increasing source.connect_timeout_seconds in your config, since a slow network path can trip the default timeout even when the connection eventually succeeds.

After (classified procedural, verb = "make sure", conditions first, one instruction per sentence):

Connection timeouts. sqlpipe stops with dial tcp: i/o timeout when it cannot reach the Postgres port (5432 by default).

1. Make sure that the host that runs sqlpipe can reach the Postgres port. A firewall or security group usually blocks it.
2. If the database is managed (RDS, Cloud SQL), make sure that the instance accepts connections from the IP of sqlpipe.
3. If the network is slow, increase source.connect_timeout_seconds in the configuration.

What changed: 40-word sentences split under 20; "you're" expanded; "check/confirm" collapsed to "make sure that"; every condition moved before its command; "etc." removed; code and error strings untouched.

Limits

STE is for technical facts and instructions. Do not apply it to marketing copy, blog voice, or brand writing — it deletes persuasion by design. When a user asks for STE on marketing text, say so and offer it for the docs instead.

This skill is an unofficial aid. It is not affiliated with or endorsed by ASD or STEMG, and no tool can guarantee STE compliance. ASD-STE100 is a registered trademark of ASD. The official standard is a free download at asd-ste100.org.

References

• references/checklist.md — full verification pass with searchable patterns, for check mode and final audits
• references/use-cases.md — long-form adaptations: error messages, runbooks, incident reports, commits, UI copy, i18n