[ADD] purchase: How to Manage Vendor Bills

https://docs.google.com/document/d/1W6ybn8fLr6Y9QDvbARCOG_z0H4sjxz222SmhnMM_kd8/edit#heading=h.teahchhagxca

purchase/purchases/rfq/bills.rst

@@ -1,3 +1,227 @@
 ==============================
 How to control supplier bills?
-==============================
+==============================
+
+The **Purchase** application allows you to manage your purchase orders,
+incoming products, and vendor bills all seamlessly in one place.
+
+If you want to set up a vendor bill control process, the first thing you
+need to do is to have purchase data in Odoo. Knowing what has been
+purchased and received is the first step towards understanding your
+purchase management processes.
+
+Here is the standard work flow in Odoo:
+
+1.  You begin with a **Request for Quotation (RFQ)** to send out to your
+    vendor(s).
+
+2.  Once the vendor has accepted the RFQ, confirm the RFQ into a
+    **Purchase Order (PO)**.
+
+3.  Confirming the PO generates an **Incoming Shipment** if you purchased
+    any stockable products.
+
+4.  Upon receiving a **Vendor Bill** from your Vendor, validate the bill
+    with products received in the previous step to ensure accuracy.
+
+This process may be done by three different people within the company,
+or only one.
+
+Configuration
+=============
+
+Installing the Purchase and Inventory applications
+--------------------------------------------------
+
+From the **Apps** application, search for the **Purchase** module and
+install it. Due to certain dependencies, installing purchase will
+automatically install the **Inventory** and **Accounting** applications.
+
+Creating products
+-----------------
+
+Creating products in Odoo is essential for quick and efficient
+purchasing within Odoo. Simply navigate to the **Products** submenu under
+**Purchase**, and click **Create**.
+
+.. image:: media/bills03.png
+    :align: center
+
+When creating the product, Pay attention to the **Product Type** field,
+as it is important:
+
+-   Products that are set as **Stockable** or **Consumable** will allow you
+    to keep track of their inventory levels. These options imply
+    stock management and will allow for receiving these kinds of
+    products.
+
+-   Conversely, products that are set as a **Service** or **Digital Product**
+    will not imply stock management, simply due to the fact that
+    there is no inventory to manage. You will not be able to receive
+    products under either of these designations.
+
+.. tip::
+    It is recommended that you create a **Miscellaneous** product for all 
+    purchases that occur infrequently and do not require inventory 
+    valuation or management. If you create such a product, it is recommend 
+    to set the product type to **Service**.
+
+Managing your Vendor Bills
+==========================
+
+Purchasing products or services
+-------------------------------
+
+From the purchase application, you can create a purchase order with as
+many products as you need. If the vendor sends you a confirmation or
+quotation for an order, you may record the order reference number in the
+**Vendor Reference** field. This will enable you to easily match the PO
+with the the vendor bill later (as the vendor bill will probably include
+the Vendor Reference)
+
+.. image:: media/bills04.png
+    :align: center
+
+Validate the purchase order and receive the products from the **Inventory**
+application.
+
+Receiving Products
+------------------
+
+If you purchased any stockable products that you manage the inventory
+of, you will need to receive the products from the **Inventory** application
+after you confirm a purchase order. From the **Inventory** dashboard, you
+should see a button linking you directly to the transfer of products.
+This button is outlined in red below:
+
+.. image:: media/bills07.png
+    :align: center
+
+Navigating this route will take you to a list of all orders awaiting to
+be received.
+
+.. image:: media/bills05.png
+    :align: center
+
+If you have a lot of awaiting orders, apply a filter using the search
+bar in the upper right. With this search bar, you may filter based on
+the **Vendor** (or **Partner**), the product, or the source document, also known as
+the reference of your purchase order. You also have the capability to
+group the orders by different criteria under **Group By**. Selecting an
+item from this list will open the following screen where you then will
+receive the products.
+
+.. image:: media/bills02.png
+    :align: center
+
+Purchasing **Service** products does not trigger a delivery order.
+
+Managing Vendor Bills
+---------------------
+
+When you receive a **Vendor Bill** for a previous purchase, be sure to
+record it in the **Purchases** application under the **Control Menu**. You
+need to create a new vendor bill even if you already registered a
+purchase order.
+
+.. image:: media/bills06.png
+    :align: center
+
+The first thing you will need to do upon creating a **Vendor Bill** is to
+select the appropriate **Vendor** as this will also pull up any associated
+accounting or pricelist information. From there, you can choose to
+specify any one or multiple purchase orders to populate the vendor bill
+with. When you select a purchase order from the list, Odoo will pull any
+uninvoiced products associated to that purchase order and automatically
+populate that information below. If you are having a hard time finding
+the appropriate vendor bill, you may search through the list by
+inputting the vendor reference number or your internal purchase order
+number.
+
+.. image:: media/bills01.png
+    :align: center
+
+While the invoice is in draft state, you can make any modifications you
+need (i.e. remove or add product lines, modify quantities, and change
+prices).
+
+.. note:: 
+    Your vendor may send you several bills for the same purchase order if:
+
+    1. Your vendor is in back-order and is sending you invoices as they 
+       ship the products.
+
+    2. Your vendor is sending you a partial bill or asking for a deposit.
+
+Every time you record a new vendor bill, Odoo will automatically
+populate the product quantities based on what has been received from the
+vendor. If this value is showing a zero, this means that you have not
+yet received this product and simply serves as a reminder that the
+product is not in hand and you may need to inquire further into this. At
+any point in time, before you validate the vendor bill, you may override
+this zero quantity.
+
+Vendor Bill Matching
+====================
+
+What to do if your vendor bill does not match what you received
+---------------------------------------------------------------
+
+If the bill you receive from the vendor has different quantities than
+what Odoo automatically populates as quantities, this could be due to
+several reasons:
+
+-   The vendor is incorrectly charging you for products and/or services
+    that you have not ordered.
+
+-   The vendor is billing you for products that you might not have
+    received yet, as the invoicing control may be based on ordered or
+    received quantities.
+
+-   Or the vendor did not bill you for previously purchased products.
+
+In these instances it is recommended that you verify that the bill, and
+any associated purchase order to the vendor, are accurate and that you
+understand what you have ordered and what you have already received.
+
+If you are unable to find a purchase order related to a vendor bill,
+this could be due to one of a few reasons:
+
+-   The vendor has already invoiced you for this purchase order,
+    therefore it is not going to appear anywhere in the selection.
+
+-   Someone in the company forgot to record a purchase order for this
+    vendor.
+
+-   Or the vendor is charging you for something you did not order.
+
+How product quantities are managed
+----------------------------------
+
+By default, services are managed based on ordered quantities, while
+stockables and consumables are managed based on received quantities.
+
+If you need to manage products based on ordered quantities over received
+quantities, you will need to enable **Debug Mode** from the **About Odoo**
+information. Once debug mode is activated, select the product(s) you
+wish to modify, and you should see a new field appear, labeled **Control
+Purchase Bills**.
+
+.. image:: media/bills08.png
+    :align: center
+
+You can then change the default management method for the selected
+product to be based on either:
+
+-  Ordered quantities
+
+-  Received quantities
+
+Batch Billing
+-------------
+
+When creating a vendor bill and selecting the appropriate purchase
+order, you may continue to select additional purchase orders and Odoo
+will add the additional line items from that purchase order. If you
+have not deleted the previous line items from the first purchase order
+the bill will be linked to all the appropriate purchase orders.