Minor documentation adjustments.

doc/submission.md

@@ -185,27 +185,27 @@ Example of a table representing an artifact with two files:
       <td>still_image</td>
       <td>Sg9hYIISjRjlkP62</td>
       <td>my_collection/artifact1</td>
+      <td>12-07-2002</td>
       <td>My first deposited artifact</td>
-      <td>2002</td>
     </tr>
     <tr>
       <td>still_image_file</td>
       <td>7hic19YTXA8Fudxo</td>
       <td>my_collection/artifact1/file1.tiff</td>
-      <td>2025</td>
+      <td>09-22-2025</td>
       <td></td>
     </tr>
     <tr>
       <td>still_image_file</td>
       <td>Z509TdNhpTjPYDS4</td>
       <td>my_collection/artifact1/file2.pdf</td>
-      <td>2025</td>
+      <td>09-23-2025</td>
       <td></td>
     </tr>
   </tbody>
 </table>
 
-Note the difference between the `still_imge` and the `still_image_file`
+Note the difference between the `still_image` and the `still_image_file`
 resources. We will get back to it further down.
 
 #### Multi-valued fields
@@ -261,7 +261,7 @@ to determine whether a row in the table is a continuation from the previous
 one, adding multiple values. Having a row without `content` type and with `id`
 and/or `source_path` is considered an error.
 
-#### Ordering (sorting)
+#### Ordering
 
 The ordering of rows in a laundry list determines the ordering of the resources
 in their container. The system automatically assigns an order to the resources,
@@ -374,17 +374,25 @@ These three key content types are seldom used as-is. They usually have
 sub-types, which are defined in the content model. See the content modeling
 guide for more information about sub-types.
 
+Types provided by Pocket Archive may have similar names but different uses. For
+example, the `still_image` type, a sub-type of `artifact`, designates a visual
+object, e.g. a photograh. `still_image_file` may be the capture (e.g. scan) of
+that object, but also the capture of a `text` artifact if it is the scan of a
+book page.
+
 Also see the [sample laundry
-list](../test/sample_submission/pkar_submisson-demo.csv) for examples of
-artifacts, files, and bricks making up a two-sided postcard.
+list](../test/sample_submission/pkar_submission-demo.csv) for examples of
+artifacts, files, and bricks making up a two-sided postcard. (Note: download
+file and open it with a spreadsheet editor. The current platform shows the
+raw file.)
 
 ### Submission ID and submission name
 
 Each submission gets a randomly generated ID when it starts. This ID is
-attached to all the resources in the submission. This makes it easier to It
-also makes it possible to generate a laundry list that contains exactly the
-same resources that were originally submitted (possibly with added
-auto-generated implicit resources).
+attached to all the resources in the submission. This makes it easier to find
+out later on when and how a certain resource was submitted. It also makes it
+possible to generate a laundry list that contains all the resources of the
+original submission.
 
 The ID is automatically generated and system-controlled. It cannot be changed.
 A submission can also have a name, which is optional and user-defined. The
@@ -412,7 +420,7 @@ submissions.
 
 #### Implicit resources
 
-Some implicit resources are created 
+TODO
 
 #### ID generation