Sometimes an emoji is just an emoji. Sometimes it may be a threat.

And with only a few seconds to spare, Facebook moderators have to make the call — even if the text that accompanies the laughing yellow face is in an unfamiliar language.

To help with those decisions, Facebook has created a list of guidelines for what its two billion users should be allowed to say. The rules, which are regularly updated, are then given to its moderators.

For Facebook, the goal is clarity. But for the thousands of moderators across the world, faced with navigating this byzantine maze of rules as they monitor billions of posts per day in over 100 languages, clarity is hard to come by.

Facebook keeps its rulebooks and their existence largely secret. But The New York Times acquired 1,400 pages from these guidelines, and found problems not just in how the rules are drafted but in the way the moderation itself is done.