Chapter 3: Languages (and Language Subsets): Coding Guidelines and Rust

Coding Guidelines 

Functional safety standards do not specify a particular programming language: any language can be used as long as the scope and limitations of the language are understood. That is why many functional safety standards support or expect the use of coding guidelines to implement a language subset. 

Implementing a language subset reduces exposure to risky constructs that are legal in the language but problematic in safety-critical systems.