The controlled vocabulary
The first rule of writing is the choice of words. Simplified Technical English (ASD-STE100) controls that choice with a dictionary. The dictionary lists the words a writer can use, and the words a writer must not use. This is the core of a controlled language: you do not write with all of English. You write with a small, agreed subset.
The dictionary works together with the writing rules. The rules tell you how to build sentences. The dictionary tells you which words to put in them.
Approximately 900 approved words
The STE dictionary contains about 900 approved words. Each approved word has one meaning and one part of speech.
This is the key idea. In standard English, one word can have many meanings and can act as several parts of speech. STE removes that ambiguity. An approved word is approved for a single sense and a single grammatical role.
For example, STE approves start. You use start instead of its synonyms begin, commence, initiate, or originate. One concept gets one word, so the reader never has to choose between near-equivalents.
The goal is not a smaller vocabulary for its own sake. The goal is predictability. When every approved word maps to exactly one idea, a reader (often a non-native English speaker, often under time pressure) can decode a procedure without guessing.
Approved versus unapproved words
The dictionary has two sides.
- Approved words — the roughly 900 words a writer can use, each shown with its one approved meaning and part of speech, with usage examples.
- Unapproved words — a longer list (about 1,200 entries) of words that are not approved, each paired with an approved alternative to use instead.
So the dictionary does not only block words. For most unapproved words it tells you what to write in their place. This is what makes STE usable in practice: when you reach for a banned word, the dictionary hands you the approved one.
The table below is illustrative — a small sample in the spirit of the dictionary, not a quotation of it. The verified, authoritative entries are in the official ASD-STE100 dictionary.
| Unapproved | Approved alternative | Why |
|---|---|---|
| commence, initiate | start | One approved word for the concept. |
| terminate | stop, end | Choose the approved word that fits the meaning. |
| utilize | use | Plain word, single meaning. |
| in the event that | if | Short, direct conditional. |
| approximately | about | Simpler everyday word. |
| component | part | The approved general term. |
A word can be approved as one part of speech and unapproved as another. For example, a word approved only as a noun must not be used as a verb. The dictionary entry states the role, and STE writing rules enforce it. Always check the part of speech, not just the spelling.
Technical nouns and technical verbs: the project exceptions
A controlled dictionary of 900 words cannot name a hydraulic accumulator, a torque wrench, or the act of safety-wiring a bolt. Real maintenance work needs domain vocabulary. STE handles this with two categories of exception:
- Technical nouns — noun terms specific to a company, industry, or subject field (for example, landing gear, accumulator, bleed-air valve).
- Technical verbs — verb terms specific to that field (for example, to safety-wire, to ream, to crimp).
The dictionary does not list these terms. They are defined by the project, the industry, or the subject field — not by the central dictionary. STE gives rules for using them correctly, but the actual terms belong to the project.
There is an important consequence. If a word that is not approved in the dictionary appears as part of a technical noun or technical verb, it automatically becomes part of that term and is therefore acceptable. The word is not approved on its own, but it is allowed inside the agreed technical term.
A project must decide and record its own technical nouns and technical verbs. In an S1000D project that decision lives in the business rules, and the machine-checkable subset lives in the BREX data module. A grammar/style checker can flag any word that is neither in the STE dictionary nor in the project's approved technical-term list.
In ASD-STE100 Issue 9 (15 January 2025), the labels for these categories were modernized — the earlier "technical name" became technical noun, and "technical verb" became technical verb (term) — to align the specification with the terminology of ISO 1087-1:2019. The principle is unchanged: the dictionary controls general vocabulary, and the project controls its own technical terms.
Why this matters for a CSDB
S1000D stores reusable data modules in a common source database. A data module written once may be reused, translated, and read by many people. A controlled vocabulary makes that reuse safe:
- Consistency — the same concept is always the same word across thousands of modules.
- Translation — one meaning per word reduces translation cost and error.
- Validation — because the rules are explicit, a tool can check a module against the approved words and the project's technical terms.
STE is a separate specification from S1000D, but the two are designed to work together. S1000D is the structure; STE is the prose inside that structure.
Sources
- ASD-STE100 — About STE (official) — the dictionary holds ~900 approved words, each with one meaning and one part of speech, plus ~1,200 unapproved words with alternatives; technical nouns and technical verbs are project-defined.
- ASD-STE100 — FAQ (official) — approved vs unapproved words, the "use start not begin/commence/initiate/originate" example, and how non-approved words become acceptable inside a technical noun or verb.
- ASD — Simplified Technical English — ASD-STE100 overview and governance.
- tcworld — ASD-STE100 Issue 9 — Issue 9 (15 January 2025); 53 writing rules; the "technical name" / "technical verb" labels were replaced with "technical noun" / "technical verb (term)" to align with ISO 1087-1:2019.