Meta terminology
DAP
Daily Active People
Core Meta engagement metric counting the distinct people active on a platform in a day, reported per app and across the family. The source document lists it among the four teen metrics a "Youth Defense Task Force" was formalised to protect - "teen MAP, DAP, TS and PS" - from "experiments and rollouts across Facebook that negatively affect teen metrics".
Sources
Plaintiffs' filingComplaint for Injunctive and Other Relief, California v. Meta
Internal documentH2/H1 2018 Youth Team Review