Understanding all of the rules, features, and mechanisms of a programming language, and optimizing for simplicity, accuracy, and modularity within the rules of the programming language to implement solutions.
This competency area includes identifying what makes a developer proficient in a given programming language.
Writing code - Ability to write code in a given language and is proficient in using common language features. Ability to produce a functional program with ease.
Optimizing code - Optimizing source code of a given language.