Magento_PurchaseOrder
Overview
 The PurchaseOrder module contains functionality for creating purchase orders in a B2B environment. When enabled, all orders created within the company will be created as purchase orders. This allows B2B users to enforce purchasing rules and worflows within a Magento store. 
Installation details
 The PurchaseOrder module has dependencies on the following modules: 
- Module_Authorization
 - Module_Catalog
 - Module_Checkout
 - Module_Company
 - Module_Customer
 - Module_Directory
 - Module_Msrp
 - Module_Negotiable_Quote
 - Module_Payment
 - Module_Quote
 - Module_Sales
 - Module_Sales_Sequence
 - Module_Store
 - Module_Tax
 - Module_Theme
 - Module_Ui
 
 which must be installed and enabled first. This module does not create any backward incompatible changes. It can be uninstalled or deactivated at any time. 
Structure
 Learn about a typical file structure for a Magento 2 module. 
Extensibility
Extension developers can interact with the Magento_PurchaseOrder module. For more information about the Magento extension mechanism, see Magento plug-ins.
The Magento dependency injection mechanism enables you to override the functionality of the Magento_PurchaseOrder module.
Layouts
This module introduces the following layouts and layout handles in the view/frontend/layout directory:
email_purchaseorder_detailspurchaseorder_purchaseorder_indexpurchaseorder_purchaseorder_successpurchaseorder_purchaseorder_view
UI components
You can extend the purchase order listings using the company_purchaseorder_listing.xml and my_purchaseorder_listing.xml configuration files.
Additional information
 Check the B2B release notes for more information on new changes.