Controlled natural languages (CNLs) are subsets of natural languages,
obtained by restricting the grammar and vocabulary in order to reduce or
eliminate ambiguity and complexity. Traditionally, controlled languages
fall into two major types: those that improve readability for human
readers (e.g. non-native speakers), and those that enable reliable
automatic semantic analysis of the language.

Languages of the first type (often called "simplified" or "technical"
languages), for example ASD Simplified Technical English, Caterpillar
Technical  English,  IBM's  Easy  English,  are  used  in industry to
increase the quality of technical documentation, and possibly simplify
the (semi-) automatic translation of the documentation. These languages
restrict the writer by general rules such as "write short and
grammatically simple sentences", "use nouns instead of pronouns", "use
determiners", and "use active instead of passive".

Languages of the second type have a formal logical basis, i.e. they have
a formal syntax and semantics, and can be mapped to an existing formal
language, such as first-order logic. Thus, those languages can be used
as knowledge-representation languages, and writing of those languages is
supported by fully automatic consistency and redundancy checks, query
answering, etc.

(en.wikipedia.org/wiki/Controlled_natural_language)