Is there a provision to book sales order from customer on OM with Item description only ?

Hello Experts,

Need your advice on the below scenario.

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My client is a SCM service provider. It receives sales orders [for both materials and services] from its customers and creates back to back purchase orders to fulfill these orders. There are blanket or contracts purchase agreements already in place between my client and its suppliers. Whenever it receives a sales order for items [having item number] from its customers, back to back purchase release is created against the BPA for fulfillment.

For inventory items [having item number] sales order booking is possible but can you advise how orders for services where i do not have an item number [i.e. it is a service item identified by description and do not have an item number in item master] be booked ?