The GCS2 is a Demand-Based Supply Chain Management (SCM) Methodology that aligns the entire supply chain management activities towards market requirements planning.
Why Demand-Based?
SCM Methodologies from MRP2TM to SCORTM do not cover important areas of the SCM such Sales, Marketing, Trade Marketing, Systems (Planning vs. Transactional, etc.), or even the role of the Processes (such as Procurement where its role is usually contained to the Horizon of the last Planning Requisition rather than the entire Planning Horizon).
Also these Methodologies have, usually, a consensual character rather than a linear (from the Market) which looses the focus often (Flat Earth Syndrome).
These and other reasons is why the Demand-Based SCM approach is gaining preference.