Glossary · 3 · Tasks and minimalism
Controlled language
Also known as: Controlled natural language, CNL
German: kontrollierte Sprache
In technical communication, a controlled language is a restricted form of a natural language that limits vocabulary, word meanings, grammar and style through explicit rules, in order to make texts clearer and more consistent for their readers and easier to translate or to process by machine.
- Writing rules
- Minimalism
- Translation
In one sentence
A controlled language restricts vocabulary, grammar and style of a natural language by rules to make texts clearer and easier to translate.
Example
A controlled-language rule set for maintenance instructions allows “close” only in the sense of moving a valve to the closed position, requires one instruction per sentence and the imperative for actions, and forbids the passive voice in procedures.
How it applies
- Range: Tobias Kuhn’s survey (2014) lists 100 English-based controlled natural languages from 1930 onward and notes three main purposes: improving communication among humans, improving translation, and providing natural representations of formal notations. Controlled languages for technical documentation belong mainly to the first two.
- Typical rules: an approved vocabulary with one meaning per word, approved terms for the product, limits on sentence length, one instruction per sentence, the active voice and the imperative for procedures, and rules for warnings. The rules are usually checked by editorial review and, increasingly, by style-checking software.
- Machinery and aerospace documentation: The best-known example is Simplified Technical English (ASD-STE100), developed for aircraft maintenance documentation. Company-specific controlled languages are common in machinery and automotive documentation, often together with terminology management and translation memory.
- Limits: A controlled language reduces ambiguity and variation; it does not guarantee that readers understand the text or that the content is correct. Comprehension still depends on content selection, structure, illustrations and testing with users, and safety-related information must be complete whatever the language rules allow.
Controlled language vs. plain language
Plain language is a broader approach that aims at text the intended audience can understand and use, with guidelines rather than closed rule sets. A controlled language defines explicit, checkable restrictions, often including a closed dictionary. Both can be combined.
External references
- Tobias Kuhn, “A Survey and Classification of Controlled Natural Languages,” Computational Linguistics 40(1) (2014), 121–170: https://doi.org/10.1162/coli_a_00168
- ASD-STE100 Simplified Technical English, official site of the ASD Simplified Technical English Maintenance Group: https://www.asd-ste100.org/