Madison, please stop posting GPT output. That is not a helpful solution at all.
ang - it seem that chapter 16 is discussing DBE (code-level earthquake) drifts while chapter 18 is discussing MCE level drifts. You may need to check both, so an average drift for the DBE check and max drift for the MCE check. I have not personally done this previously, and chapter 18's drift limits reference back to chapter 12, so there may be more to the story. I'll be following this post to see if anyone has experience on this topic