[ADD] inventory: new doc about inventory valuation (#501)

inventory/management/reporting.rst

@@ -6,5 +6,6 @@ Valuation Methods
    :titlesonly:
    :glob:
 
+   reporting/inventory_valuation_config
    reporting/valuation_methods_continental
    reporting/valuation_methods_anglo_saxon

inventory/management/reporting/inventory_valuation_config.rst

@@ -0,0 +1,114 @@
+=================================
+Inventory valuation configuration
+=================================
+
+Inventory valuation refers to how you value your stock. It’s a very
+important aspect of a business as the inventory can be the biggest asset
+of a company.
+
+Inventory valuation implies two main choices:
+
+-  The cost method you use to value your goods (standard, fifo, avco)
+-  The way you record this value into your accounting books (manually or automatically)
+
+Those two concepts are explained in the sections below.
+
+Costing Methods: Standard, FIFO, AVCO
+=====================================
+
+The costing method is defined in the product category. There are three
+options available. Each of them is explained in detail below.
+
+.. image:: media/inventory_valuation_config_01.png
+    :align: center
+
+Standard Price
+--------------
+
+In Standard Price, any product will be valued at a cost that you defined
+manually on the product form. Usually, this cost is an estimation based
+on the material and labor needed to obtain the product. This cost must
+be reviewed periodically.
+
+First In First Out (FIFO)
+-------------------------
+
+In FIFO, the products are valued at their purchase cost. When a product
+leaves the stock, that’s the “First in, first out” rule that applies.
+Let’s take an example: I first purchase a t-shirt for $10 and, later,
+one for $20. The first t-shirt that will go out of my stock will be
+valued at $10 and the next one at $20.
+
+.. tip::
+		Pay attention, that this is a financial FIFO. This means that the
+		locations where the products are stored don’t impact the valuation. The
+		first value “in” is the first value “out”, no matter the storage
+		location.
+
+Average Cost (AVCO)
+-------------------
+
+In AVCO, each product has the same value and this value is the average
+purchase cost of the product. Let’s take an example: I first purchase a
+t-shirt for $10 and, later, one for $20. Each t-shirt will be valued at
+$15, the average weighted purchase cost. With this costing method, the
+cost of the product is recomputed as each receipt.
+
+Inventory Valuation: Manual or Automated
+========================================
+
+There are two ways to record your inventory valuation in your accounting
+books. As the costing method, this is defined in your product category.
+Those two methods are detailed below.
+
+Manual Inventory Valuation
+--------------------------
+
+In this case, goods receipts and deliveries won’t have any direct impact
+on your accounting books. Periodically, you create a manual journal
+entry representing the value of what you have in stock. To know that
+value, go in Inventory > Reporting > Inventory Valuation.
+
++----------------------------------+---------+----------+
+|                                  | Debit   | Credit   |
++==================================+=========+==========+
+| Assets: Inventory                | X       |          |
++----------------------------------+---------+----------+
+| Expenses: Inventory Variations   |         | X        |
++----------------------------------+---------+----------+
+
+.. tip::
+		If the stock value has decreased, the assets account will be credited.
+
+Automated Inventory Valuation
+-----------------------------
+
+In that case, when a product enters or leaves your stock, an accounting
+entry will be automatically created. This means your accounting books
+are always up-to-date. This mode is dedicated to expert accountants and
+advanced users only. As opposed to periodic valuation, it requires some
+extra configuration & testing.
+
+First, you need to define the accounts that will be used for those
+accounting entries. This is done on the product category.
+
+.. image:: media/inventory_valuation_config_02.png
+    :align: center
+
+Note that the accounting entries that will be recorded will depend on
+your accounting mode: it can be continental or anglo-saxon. In
+continental accounting, the cost of a good is taken into account as soon
+as the product is received in stock. In anglo-saxon accounting, the cost
+of a good is only recorded as an expense when this good is invoiced to a
+final customer.
+
+Usually, based on your country, the correct accounting mode will be
+chosen by default. If you want to verify your accounting mode, activate
+the developer mode and open your accounting settings.
+
+.. image:: media/inventory_valuation_config_03.png
+    :align: center
+
+.. seealso::
+   * `How to do an inventory valuation? (Anglo-Saxon Accounting) <https://www.odoo.com/documentation/user/13.0/inventory/management/reporting/valuation_methods_anglo_saxon.html>`_
+   * `How to do an inventory valuation? (Continental Accounting) <https://www.odoo.com/documentation/user/13.0/inventory/management/reporting/valuation_methods_continental.html>`_