prescriptive
adj.describing rules or advice that tells you exactly what you must do. It is often used when someone is very strict about how a language or a system should be used.
adj.relating to the establishment of rules or standards that dictate how something should be done. Often contrasted with descriptive approaches that merely observe how people actually behave.
“The grammar book has a very prescriptive approach to language.”
“While some linguists prefer a descriptive view of how people speak, others follow a prescriptive style that focuses on strict rules.”
“The committee's prescriptive guidelines left little room for individual creativity, forcing all members to adhere strictly to the established formatting standards regardless of their specific project needs.”
“She doesn't follow a prescriptive plan, she says, but instead makes changes intuitively.”
“This can create tensions between ambitions for broader change and established ways of working, as well as between flexibility and more prescriptive reporting requirements.”
From Latin praescriptivus (“relating to a legal exception”), from praescript- (“directed in writing”), from the verb praescribere.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.