Blanket Agreements 
Blanket agreements are long-term arrangements between a purchasing organization and a vendor, or a sales organization and a customer, for the supply of items or provision of services over a period of time based on predefined terms and conditions. Blanket agreements can be used as a basis for expected revenue forecasts, quantity reservation, and capacity planning.
In SAP Business One, you can have two types of blanket agreements:
General blanket agreements: Are used to track fulfillment of terms to obtain a special bonus at year end, for example, for selling or purchasing a certain quantity of an item or for achieving a defined turnover.
Specific blanket agreements: Are used to track fulfillment of terms to obtain a special discount for the individual sales or purchasing transaction. They are also used to determine a delivery schedule, for example, by defining at which intervals which quantity of goods should be delivered.
If a valid blanket agreement exists with a customer or vendor, SAP Business One automatically links sales and purchasing documents to the blanket agreement. This way, the prices agreed upon with the business partners can be copied directly into the sales and purchasing documents. You can also choose to remove the link and create a sales or purchasing document that is not governed by a blanket agreement.