Prescriptive and Prescript

adjective

• Pertaining to giving directives or rules.
  • usage: "prescriptive grammar is concerned with norms of or rules for correct usage"
  • synonyms: normative

(a.) Consisting in or acquired by, immemorial or long-continued use and enjoyment; as, a prescriptive right of title; pleading the continuance and authority of long custom.

noun

• Prescribed guide for conduct or action.
  • synonyms: rule

• (n.) Direction; precept; model prescribed.
• (n.) A medical prescription.
• (a.) Directed; prescribed.