update REUSE section

Signed-off-by: Alberto Pianon <alberto@pianon.eu>

contributing/reuse.rst

@@ -17,17 +17,23 @@ All projects and files for an hosted project **MUST** be `REUSE <https://reuse.s
 compliant. REUSE requires SPDX information for each file, rules for which are
 as follows:
 
-* Any new file must have a SPDX header (copyright and license).
-* For files that don't support headers (for example binaries, patches etc.) an associated ``.license`` file must be included with the relevant SPDX information.
-* Do not add Copyright Year as part of the SPDX header information.
-* The general rule of thumb for the license of a patch file is to use the license of the component for which the patch applies.
-* When modifying a file through this contribution process, you may (but don't have to) claim copyright by adding a copyright line.
-* Never alter copyright statements made by others, but only add your own.
+* for files copyrighted by projects contributors (**"First Party Files"**):
+  *   any new file must have a SPDX header (copyright and license);
+  *   for files that don't support headers (for example binaries, patches etc.) an associated ``.license`` file must be included with the relevant SPDX information;
+  *   do not add Copyright Year as part of the SPDX header information;
+  *   the general rule for patch files is to use MIT license and *not* the license of the component for which the patch applies - the latter solution would be error-prone and hard to manage and maintain in the long run, and there may be difficult-to-handle cases (what if the patches modifies multiple files in the same component - eg. gcc - which are subject to different licenses?);
+  *   when modifying a file through this contribution process, you may (but don't have to) claim copyright by adding a copyright line;
+  *   never alter copyright statements made by others, but only add your own;
 
-Some files will make an exception to the above rules as described below:
+* for files copyrighted by third parties and just added to the project by contributors, eg. files copied from other projects or back-ported patches (**"Third Party Files"**):
+  * if upstream files already have SPDX headers, they must be left unchanged;
+  * if upstream files do *not* have SPDX headers:
+    * the exact upstream provenance (repo, revision, path) must be identified;
+    * do *not* add SPDX headers to Third Party Files;
+    * copyright and license information, as well as upstream provenance information (in the "Comment" section), must be stored in `.reuse/dep5` following `Debian dep5 specification <https://dep-team.pages.debian.net/deps/dep5/>`_ (see examples below);
+    * never use wildcards (\*) in dep5 "Files" paragraphs even if Debian specs allow it: it may lead to unnoticed errors or inconsistencies in case of future file additions that may be covered by wildcard expressions even if they have a different license
+    * in case of doubts or problems in finding the correct license and copyright information for Third Party Files, contributors may ask project's Legal Team in the project mailing list oniro-dev@eclipse.org.
 
-* Files for which copyright is not claimed and for which this information was not trivial to fetch (for example backporting patches, importing build recipes etc. when upstream doesn't provide the SPDX information in the first place)
-* license files (for example ``common-licenses`` in bitbake layers)
 
 SPDX Header Example
 -------------------
@@ -42,6 +48,29 @@ Make sure all of your submitted new files have a licensing statement in the head
      * SPDX-License-Identifier: Apache-2.0
      */
 
+
+DEP5 "Files" Paragraph Examples
+-------------------------------
+
+.. code-block:: text
+
+    Files: meta-oniro-staging/recipes-containers/buildah/buildah_git.bb
+    Copyright: OpenEmbedded Contributors
+    License: MIT
+    Comment: Recipe file for buildah copied from meta-virtualization project at
+             https://git.yoctoproject.org/meta-virtualization,
+             recipes-containers/buildah.
+             README file of meta-virtualization project states:
+             "All metadata is MIT licensed unless otherwise stated."
+
+    Files: meta-oniro-staging/recipes-devtools/ninja/ninja/0001-feat-support-cpu-limit-by-cgroups-on-linux.patch
+    Copyright: Google Inc.
+    License: Apache-2.0
+    Comment: Patch for ninja backported from Ninja project at
+            https://github.com/ninja-build/ninja, commit 540be33
+            Copyright text left as found in the header of the patched file.
+
+
 Substantial Contributions
 -------------------------