This document provides an overview of Global ATP (Available-to-Promise) capabilities in SAP APO (Advanced Planning and Optimization). It describes Global ATP concepts and components, including how ATP is embedded in the APO architecture and integrated with OLTP systems. The document outlines various Global ATP methods like basic availability checking using aggregated time series data on receipts, issues, and inventory, as well as more advanced rules-based ATP. Global ATP allows multi-step, multi-site and multi-material availability checking across the supply chain in real-time or simulation mode.