Two ways to write clearly
Writers often ask if Simplified Technical English is "just Plain English for engineers". The answer is no, although the two share many ideas. Both want the reader to understand the text quickly and correctly. Both prefer short sentences, the active voice and common words. The difference is in how strict they are, who they are for and how you can check them.
Simplified Technical English (STE) is defined in one specification, ASD-STE100. It is a controlled language. It gives a dictionary of approved words and a set of writing rules. A sentence either follows the rules or it does not. Plain English is a movement and a set of guidelines. Many governments and organisations publish their own Plain English guides. These guides give advice, not a fixed vocabulary, and they leave much to the judgement of the writer.
This page compares the two approaches and helps you decide when to use each one. You can learn more about the specification on our What is STE page, and you can find the official text through our ASD STE 100 PDF page.
Vocabulary: fixed list or free choice
The biggest difference is vocabulary. In STE, the writer uses words from the dictionary, plus technical names and technical verbs that fit the rules. Each approved word has one meaning. For example, "follow" in STE means "come after"; it does not mean "obey". This removes doubt for the reader, and it helps translators and translation tools.
Plain English asks writers to choose short, familiar words: "use" instead of "utilize", "start" instead of "commence". This advice is very similar to STE. But Plain English does not limit a word to one meaning, and it does not give a list. Two Plain English writers can choose different words for the same idea, and both can be correct.
Rules: measurable or flexible
STE gives rules that you can measure. A procedural sentence has a maximum of 20 words. A noun cluster has a maximum number of words. A procedure step is a command. Because the rules are precise, a reviewer can point to a rule when they ask for a change, and software can check part of the text automatically.
Plain English guidelines are usually expressed as advice: "keep most sentences short", "use lists where helpful", "write as you would speak". This flexibility is useful for public information, where the tone and structure change a lot from one text to another. It also means that two reviewers can disagree more easily.
Audience and purpose
STE was created for maintenance technicians who read English as a second language and who must do a task correctly and safely. The text must be understood the same way by every reader, every time. A friendly tone is less important than a single, fixed meaning.
Plain English is mainly for the general public: people who read a tax letter, an insurance policy or a health leaflet. The aim is to help people understand their rights, their duties and their options. Plain English often addresses the reader directly and can be warm and personal.
An example in both styles
Here is one original sentence and two rewrites. The first rewrite is good Plain English. The second follows STE principles.
Both rewrites are clear. The STE version avoids "turn on" and "put in", because phrasal verbs often have many meanings and can be hard to translate. It uses words with one defined meaning. The Plain English version sounds more natural in conversation. Neither is "better" in general; each is better for its purpose.
When to use STE, and when to use Plain English
- Use STE for maintenance and repair manuals, operating procedures, safety-related instructions, and any technical text that many non-native readers use or that goes into translation.
- Use STE when a contract, a customer or an industry practice requires ASD-STE100.
- Use Plain English for letters, websites, policies, forms, contracts and public information for a general audience.
- Combine them carefully. Many teams use STE for the procedures in a manual and Plain English for the introduction or marketing pages. Keep each part consistent.
What they have in common
The two approaches are allies, not rivals. Both start from the reader. Both reject unnecessary complex words, hidden actions and long, tangled sentences. If you have Plain English experience, you already have a good base for STE. You need to add the discipline of the dictionary and the specific rules. Our ASD STE 100 skill page gives a path for this, and the STE examples page shows many rewrites side by side.
Can a checker help?
Yes, for both. Readability tools can help with Plain English. For STE, our free STE checker flags long sentences, passive verbs, -ing forms, noun clusters and some words that are not approved. It is a heuristic tool, not an official conformity check. Always confirm with the official ASD STE 100 PDF.