Add more docs for Feature Layer

not complete, but progress..

docs/features/purchasing/accounting/index.rst

@@ -2,4 +2,7 @@
 Accounting
 ==========
 
-TODO
+TODO: while this is "virtually" supported as a 3rd phase, it has not
+been "fully" implemented in production.  in practice the 2nd
+(receiving) phase is taking care of accounting duties thus far.  see
+also :doc:`../receiving/accounting`.

docs/features/purchasing/index.rst

@@ -1,16 +1,21 @@
 
-Purchasing
-==========
+Purchase Orders
+===============
 
 Presumably all retailers purchase products from vendors.
 
 Rattail offers tools to assist with the various workflows involved.
-It splits the life cycle into 3 "phases" - although some purchases may
-not explicitly go through every phase.  In particular it's possible
-for the Receiving phase to include everything Accounting does.
+It splits the life cycle into 3 "phases" - Ordering, Receiving,
+Accounting.
+
+Some purchases may not explicitly go through every phase.  In
+particular it's possible for the Receiving phase to include everything
+Accounting does, and in many cases Ordering is skipped (wrt the
+system), with the PO first "entering the system" in the Receiving
+phase.
 
 .. toctree::
-   :maxdepth: 1
+   :maxdepth: 2
 
    ordering/index
    receiving/index

docs/features/purchasing/ordering/additems.rst

@@ -0,0 +1,22 @@
+
+Adding Items
+============
+
+When creating a new Purchase Order using Rattail, the user first makes
+a new Ordering batch, then adds items to it.
+
+There are three main "workflows" for adding the items.
+
+The first is where the user sees the (at first empty) batch and then
+does some sort of product lookup to identify an item to add.  The
+lookup/add process is repeated as needed.
+
+The other way is what Rattail calls the "worksheet view" - but it's
+only suitable for vendors with relatively small product lines.  In
+this view the user is presented with a "worksheet" form.  All items
+available from the vendor are visible on the worksheet, and the user
+enters desired quantities for applicable line items.
+
+There also is a mobile interface for ordering, which if used on a
+smart phone with bluetooth scanner attached, can be used for
+"in-aisle" ordering by scanning shelf tags.

docs/features/purchasing/ordering/convertpo.rst

@@ -0,0 +1,21 @@
+
+Converting a PO
+===============
+
+This is given its own section just to better clarify.
+
+The "purpose" of an Ordering batch in Rattail can vary.  Presumably
+the most common use is to actually assemble a new PO, to be submitted
+to the vendor.
+
+But this batch type can also be used to "convert" any arbitrary PO
+data, to any other format/system.  You might have multiple different
+ordering "systems" which vary by vendor etc.  If so then you could
+process PO data from each of these, as separate Ordering batches.
+Executing each batch would then produce whatever output you needed for
+them to be in a "common" format etc.
+
+Probably the most common scenario for this is where you want to import
+the PO data into your POS system.  This lets it know that the product
+is "on order" and will be what receiving happens against, once the
+order arrives from the vendor.

docs/features/purchasing/ordering/execution.rst

@@ -0,0 +1,22 @@
+
+Batch Execution
+===============
+
+Often the user will have made an Ordering batch and added items to it
+"manually" when assembling their order.
+
+But in some cases the PO data will have been imported from some other
+system, or perhaps a CSV file, with the goal being just to get it into
+the POS system.
+
+Regardless of how the batch data was obtained (e.g. from file, or user
+input), ultimately the batch will be executed.  So what does that do?
+
+This basically depends on what you need it to do...  For instance in
+the CSV file example just mentioned, if your goal is merely to get the
+PO data into the POS system, then that's what executing the batch
+should do.
+
+It is possible also to make batch execution actually "submit"
+(e.g. email) the purchase order to the vendor, although this is less
+common in practice.

docs/features/purchasing/ordering/index.rst

@@ -2,4 +2,12 @@
 Ordering
 ========
 
-TODO
+All about *ordering* product from the vendor.
+
+.. toctree::
+   :maxdepth: 3
+
+   overview
+   additems
+   execution
+   convertpo

docs/features/purchasing/ordering/overview.rst

@@ -0,0 +1,27 @@
+
+Overview
+========
+
+Ordering is when the retailer expresses to the vendor, their interest
+in purchasing some of their product for resale to their customers.
+The retailer promises to pay for the product, so the vendor should
+ship it to them ASAP.
+
+If the retailer has things "dialed in" then ordering may be fully or
+partially automatic, aka. "suggested ordering" where the purchase
+order is auto-generated based on current inventory levels.
+
+Rattail does not (yet?) offer any tools for suggested ordering.  It
+does though offer tools for the more classic scenario, where the buyer
+"manually" assembles the purchase order.
+
+It does this using a batch.  The buyer creates a new Ordering batch
+for the given vendor, and then adds items to it.
+
+Adding items may be done in a few ways.  These are discussed in
+:doc:`additems`.
+
+One way or another the batch is populated, then ultimately executed.
+Read more about that in :doc:`execution`.
+
+We also share some thoughts here, on :doc:`convertpo`.