- Level 0 - Pulls Customer and Item data
- Level 1 - Level 0 plus writes new sales orders
- Level 2 - Level 0 plus customer and sales order data is synchronized both ways
- Level 2+ - Level 2 plus something extra such as invoice history, puchrase orders, work orders, etc.
Note that each ERP has its own idiosyncrasies and you should view the How it Works page for your ERP to know exactly what data is moved and how.