Final answer:
A set of established rules that specifies how the function must be entered is known as the grammar of a particular subject.
Step-by-step explanation:
A set of established rules that specifies how the function must be entered is known as the grammar of a particular subject. In this context, the subject being referred to is computer programming, where the grammar sets the rules for how code must be written and organized in order to convey meaning and produce the desired output. These rules determine the syntax and structure of the programming language, helping programmers create functional and understandable code.