In a rule change quietly put into effect last month, Facebook now forbids users from "denying [the] existence" of certain "protected characteristic[s]," including gender identity.

The tech giant updated its "hate speech" rules on December 19 to include the provisions in official company policy for the first time. The company says "protected characteristics" include "race, ethnicity, national origin, religious affiliation, sexual orientation, caste, sex, gender, gender identity, and serious disease or disability."

A list of "dehumanizing comparisons" also prohibited by Facebook includes referring to transgender or non-binary people as "it."

Read the full guidelines here.