Clarify licenses

- add license headers to everything
- convert a few files from public domain or LGPL2.1+ to GPL2+
- some archaeology to clarify which files are from which library

46 files changed, 316 insertions, 204 deletions

diff --git a/src/xml/CMakeLists.txt b/src/xml/CMakeLists.txt
index 2a9789384..3cccc5ea6 100644
--- a/src/xml/CMakeLists.txt
+++ b/src/xml/CMakeLists.txt
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 set(xml_SRC
 	composite-node-observer.cpp
diff --git a/src/xml/attribute-record.h b/src/xml/attribute-record.h
index 91118c8a0..68080403e 100644
--- a/src/xml/attribute-record.h
+++ b/src/xml/attribute-record.h
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2017 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 /** @file
  * @brief Key-value pair representing an attribute
  */
diff --git a/src/xml/comment-node.h b/src/xml/comment-node.h
index cddd2e74b..329815215 100644
--- a/src/xml/comment-node.h
+++ b/src/xml/comment-node.h
@@ -1,17 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * @brief Comment node implementation
- */
-/* Copyright 2004-2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2018 Authors
+ * Copyright 2005 MenTaLguY <mental@rydia.net>
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
+
 #ifndef SEEN_INKSCAPE_XML_COMMENT_NODE_H
 #define SEEN_INKSCAPE_XML_COMMENT_NODE_H
 
diff --git a/src/xml/composite-node-observer.cpp b/src/xml/composite-node-observer.cpp
index cff880aad..d8dce45b0 100644
--- a/src/xml/composite-node-observer.cpp
+++ b/src/xml/composite-node-observer.cpp
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 /*
  * Inkscape::XML::CompositeNodeObserver - combine multiple observers
  *
diff --git a/src/xml/composite-node-observer.h b/src/xml/composite-node-observer.h
index c941acee8..73d0b1442 100644
--- a/src/xml/composite-node-observer.h
+++ b/src/xml/composite-node-observer.h
@@ -1,15 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * Inkscape::XML::CompositeNodeObserver - combine multiple observers
- */
-/* Copyright 2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2018 Author
+ * Copyright 2005 MenTaLguY <mental@rydia.net>
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_COMPOSITE_NODE_OBSERVER_H
diff --git a/src/xml/croco-node-iface.cpp b/src/xml/croco-node-iface.cpp
index f9bb66532..390c7b13e 100644
--- a/src/xml/croco-node-iface.cpp
+++ b/src/xml/croco-node-iface.cpp
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 #include <cstring>
 #include <string>
 #include <glib.h>
diff --git a/src/xml/croco-node-iface.h b/src/xml/croco-node-iface.h
index 2e035c31f..2965adef6 100644
--- a/src/xml/croco-node-iface.h
+++ b/src/xml/croco-node-iface.h
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 #ifndef INKSCAPE_SP_REPR_NODE_IFACE_H
 #define INKSCAPE_SP_REPR_NODE_IFACE_H
 
diff --git a/src/xml/document.h b/src/xml/document.h
index f9a1d8533..92878b26e 100644
--- a/src/xml/document.h
+++ b/src/xml/document.h
@@ -1,15 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
- * @brief Interface for XML documents
- */
-/* Copyright 2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ *  Interface for XML documents
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2011 Authors
+ * Copyright 2005 MenTaLguY <mental@rydia.net>
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_SP_REPR_DOC_H
diff --git a/src/xml/element-node.h b/src/xml/element-node.h
index 99598241a..376790feb 100644
--- a/src/xml/element-node.h
+++ b/src/xml/element-node.h
@@ -1,15 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * @brief Element node implementation
- */
-/* Copyright 2004-2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2018 Authors
+ * Copyright 2004-2005 MenTaLguY <mental@rydia.net>
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_ELEMENT_NODE_H
diff --git a/src/xml/event-fns.h b/src/xml/event-fns.h
index 5e3b43ad8..f3a6e522e 100644
--- a/src/xml/event-fns.h
+++ b/src/xml/event-fns.h
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2013 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 #ifndef SEEN_INKSCAPE_XML_SP_REPR_ACTION_FNS_H
 #define SEEN_INKSCAPE_XML_SP_REPR_ACTION_FNS_H
 
diff --git a/src/xml/event.cpp b/src/xml/event.cpp
index ecb6d0130..481c12bb6 100644
--- a/src/xml/event.cpp
+++ b/src/xml/event.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Repr transaction logging
  *
@@ -10,7 +11,7 @@
  * Copyright (C) 2001-2002 Ximian, Inc.
  * g++ port Copyright (C) 2003 Nathan Hurst
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <glib.h> // g_assert()
diff --git a/src/xml/event.h b/src/xml/event.h
index 8c7a40327..f8e832621 100644
--- a/src/xml/event.h
+++ b/src/xml/event.h
@@ -1,18 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * @brief Event object representing a change of the XML document
- */
-/* Authors:
+ *//*
+ * Authors:
  *   Unknown author(s)
  *   Krzysztof Kosiński <tweenk.pl@gmail.com> (documentation)
  *
- * Copyright 2008 Authors
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_SP_REPR_ACTION_H
diff --git a/src/xml/helper-observer.cpp b/src/xml/helper-observer.cpp
index 9ba1d7da3..340e7627a 100644
--- a/src/xml/helper-observer.cpp
+++ b/src/xml/helper-observer.cpp
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 
 #include "helper-observer.h"
 
diff --git a/src/xml/helper-observer.h b/src/xml/helper-observer.h
index 53f4c80e6..fc8a3f75c 100644
--- a/src/xml/helper-observer.h
+++ b/src/xml/helper-observer.h
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 #ifndef SEEN_XML_HELPER_OBSERVER
 #define SEEN_XML_HELPER_OBSERVER
 
diff --git a/src/xml/invalid-operation-exception.h b/src/xml/invalid-operation-exception.h
index d9d743557..e43529e14 100644
--- a/src/xml/invalid-operation-exception.h
+++ b/src/xml/invalid-operation-exception.h
@@ -1,15 +1,13 @@
-/*
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
  * Inkscape::XML::InvalidOperationException - invalid operation for node type
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2010 Authors
  * Copyright 2004-2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
- *
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_INVALID_OPERATION_EXCEPTION_H
diff --git a/src/xml/log-builder.cpp b/src/xml/log-builder.cpp
index 0b17e41c4..e89be2ef3 100644
--- a/src/xml/log-builder.cpp
+++ b/src/xml/log-builder.cpp
@@ -1,16 +1,13 @@
-/**
- * @file
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
  * Object building an event log.
- */
-/* Copyright 2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2018 Authors
+ * Copyright 2005 MenTaLguY <mental@rydia.net>
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "xml/log-builder.h"
diff --git a/src/xml/log-builder.h b/src/xml/log-builder.h
index d6505ddcb..9407a88fa 100644
--- a/src/xml/log-builder.h
+++ b/src/xml/log-builder.h
@@ -1,14 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * @brief Object building an event log
- */
-/* Copyright 2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
+ *//*
+ * Authors: see git history
  *
- * See the file COPYING for details.
+ * Copyright (C) 2018 Authors
+ * Copyright 2005 MenTaLguY <mental@rydia.net>
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_LOG_BUILDER_H
diff --git a/src/xml/node-event-vector.h b/src/xml/node-event-vector.h
index 16add2960..518bc625a 100644
--- a/src/xml/node-event-vector.h
+++ b/src/xml/node-event-vector.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * @brief Deprecated structure for a set of callbacks for node state changes
  */
@@ -8,7 +9,7 @@
  * Copyright (C) 1999-2002 Lauris Kaplinski and Frank Felfe
  * Copyright (C) 2000-2002 Ximian, Inc.
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_SP_REPR_EVENT_VECTOR
diff --git a/src/xml/node-fns.cpp b/src/xml/node-fns.cpp
index 938d36281..c996cfd97 100644
--- a/src/xml/node-fns.cpp
+++ b/src/xml/node-fns.cpp
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 #ifdef HAVE_CONFIG_H
 #endif
 
diff --git a/src/xml/node-fns.h b/src/xml/node-fns.h
index c18201ff4..82724e21e 100644
--- a/src/xml/node-fns.h
+++ b/src/xml/node-fns.h
@@ -1,18 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * @brief Helper functions for XML nodes
- */
-/* Authors:
+ *//*
+ * Authors:
+ *   see git history
  *   Unknown author
  *   Krzysztof Kosiński <tweenk.pl@gmail.com> (documentation)
  *
- * Copyright 2008 Authors
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_XML_NODE_FNS_H
diff --git a/src/xml/node-iterators.h b/src/xml/node-iterators.h
index 4e4b92b4d..11c9450b0 100644
--- a/src/xml/node-iterators.h
+++ b/src/xml/node-iterators.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Node iterators
  *
@@ -6,7 +7,7 @@
  *
  * Copyright (C) 2004 MenTaLguY
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_SP_REPR_ITERATORS_H
diff --git a/src/xml/node-observer.h b/src/xml/node-observer.h
index 295d618b5..043ea2b32 100644
--- a/src/xml/node-observer.h
+++ b/src/xml/node-observer.h
@@ -1,18 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * @brief Interface for XML node observers
- */
-/* Authors:
+ *//*
+ * Authors:
  *   MenTaLguY <mental@rydia.net>
  *   Krzysztof Kosiński <tweenk.pl@gmail.com> (documentation)
- *
- * Copyright 2005-2008 Authors
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ * 
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+/** @file
  */
 
 #ifndef SEEN_INKSCAPE_XML_NODE_OBSERVER_H
diff --git a/src/xml/node.h b/src/xml/node.h
index 2ccc1fbe1..4d739f338 100644
--- a/src/xml/node.h
+++ b/src/xml/node.h
@@ -1,18 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * @brief Interface for XML nodes
- */
+ *//*
 /* Authors:
  *   MenTaLguY <mental@rydia.net>
  *   Krzysztof Kosiński <tweenk.pl@gmail.com> (documentation)
  *
- * Copyright 2005-2008 Authors
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_NODE_H
diff --git a/src/xml/pi-node.h b/src/xml/pi-node.h
index 65b2f3482..2ec7942ea 100644
--- a/src/xml/pi-node.h
+++ b/src/xml/pi-node.h
@@ -1,14 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
- * @brief Processing instruction node implementation
- */
-/* Copyright 2004-2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
+ *  Processing instruction node implementation
+ *//*
+ * Authors: see git history
  *
- * See the file COPYING for details.
+ * Copyright (C) 2018 Authors
+ * Copyright 2004-2005 MenTaLguY <mental@rydia.net>
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_PI_NODE_H
diff --git a/src/xml/quote-test.h b/src/xml/quote-test.h
index bc01ec4e9..7e08b8ddc 100644
--- a/src/xml/quote-test.h
+++ b/src/xml/quote-test.h
@@ -1,8 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ * Initial author: Peter Moulder.
+ *
+ * Copyright (C) 2013 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 #include <cxxtest/TestSuite.h>
 #include "streq.h"
 
-/* Initial author: Peter Moulder.
-   Hereby released into the Public Domain. */
 
 #include <cstring>
 #include <functional>
diff --git a/src/xml/quote.cpp b/src/xml/quote.cpp
index b889b890d..148cb9d30 100644
--- a/src/xml/quote.cpp
+++ b/src/xml/quote.cpp
@@ -1,10 +1,13 @@
-/** \file
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
  * @brief XML quoting routines
  *//*
  * Authors:
+ * see git history
  *   Krzysztof Kosiński <tweenk.pl@gmail.com>
- * 
- * This file is in the public domain.
+ *
+ * Copyright (C) 2015 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "xml/quote.h"
diff --git a/src/xml/quote.h b/src/xml/quote.h
index 393bdf46e..a2e5950d2 100644
--- a/src/xml/quote.h
+++ b/src/xml/quote.h
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2014 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 #ifndef SEEN_XML_QUOTE_H
 #define SEEN_XML_QUOTE_H
 
diff --git a/src/xml/rebase-hrefs-test.h b/src/xml/rebase-hrefs-test.h
index e00337836..a6117b8db 100644
--- a/src/xml/rebase-hrefs-test.h
+++ b/src/xml/rebase-hrefs-test.h
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2011 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 #include <cxxtest/TestSuite.h>
 
 #include <cstdlib>
diff --git a/src/xml/rebase-hrefs.cpp b/src/xml/rebase-hrefs.cpp
index c6276a610..36f8b7065 100644
--- a/src/xml/rebase-hrefs.cpp
+++ b/src/xml/rebase-hrefs.cpp
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 
 #include <glibmm/convert.h>
 #include <glibmm/miscutils.h>
diff --git a/src/xml/rebase-hrefs.h b/src/xml/rebase-hrefs.h
index 12e521dea..afab3e4d2 100644
--- a/src/xml/rebase-hrefs.h
+++ b/src/xml/rebase-hrefs.h
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2014 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 #ifndef REBASE_HREFS_H_SEEN
 #define REBASE_HREFS_H_SEEN
 
diff --git a/src/xml/repr-action-test.h b/src/xml/repr-action-test.h
index 3769b8b28..29df246e2 100644
--- a/src/xml/repr-action-test.h
+++ b/src/xml/repr-action-test.h
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2012 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 #include <cxxtest/TestSuite.h>
 
 #include <cstdlib>
diff --git a/src/xml/repr-css.cpp b/src/xml/repr-css.cpp
index 9a0ba48de..5db698406 100644
--- a/src/xml/repr-css.cpp
+++ b/src/xml/repr-css.cpp
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 /*
  *   bulia byak <buliabyak@users.sf.net>
  *   Tavmjong Bah <tavmjong@free.fr>  (Documentation)
diff --git a/src/xml/repr-io.cpp b/src/xml/repr-io.cpp
index 258f50fe5..032d956dd 100644
--- a/src/xml/repr-io.cpp
+++ b/src/xml/repr-io.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Dirty DOM-like  tree
  *
@@ -7,7 +8,7 @@
  *
  * Copyright (C) 1999-2002 Lauris Kaplinski
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <cstring>
diff --git a/src/xml/repr-sorting.cpp b/src/xml/repr-sorting.cpp
index 75fb74166..325b2a6c1 100644
--- a/src/xml/repr-sorting.cpp
+++ b/src/xml/repr-sorting.cpp
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 
 #include "util/longest-common-suffix.h"
 #include "xml/repr.h"
diff --git a/src/xml/repr-sorting.h b/src/xml/repr-sorting.h
index dddb8588c..c11162381 100644
--- a/src/xml/repr-sorting.h
+++ b/src/xml/repr-sorting.h
@@ -1,9 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * TODO: insert short description here
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2011 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
 /** @file
  * @brief Some functions relevant sorting reprs by position within document.
  * @todo Functions in this file have non-English names. Determine what they do and rename
  *       accordingly.
  */
- 
+
 #ifndef SEEN_XML_REPR_SORTING_H
 #define SEEN_XML_REPR_SORTING_H
 
diff --git a/src/xml/repr-util.cpp b/src/xml/repr-util.cpp
index 7d043f7e5..a5dea02a2 100644
--- a/src/xml/repr-util.cpp
+++ b/src/xml/repr-util.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /**
  * @file
  * Miscellaneous helpers for reprs.
@@ -12,7 +13,7 @@
  * Copyright (C) 2000-2001 Ximian, Inc.
  * g++ port Copyright (C) 2003 Nathan Hurst
  *
- * Licensed under GNU GPL
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <cstring>
diff --git a/src/xml/repr.cpp b/src/xml/repr.cpp
index 23485876c..89885865c 100644
--- a/src/xml/repr.cpp
+++ b/src/xml/repr.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** \file
  * A few non-inline functions of the C facade to Inkscape::XML::Node.
  */
@@ -11,7 +12,7 @@
  * Copyright (C) 2000-2002 Ximian, Inc.
  * g++ port Copyright (C) 2003 Nathan Hurst
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #define noREPR_VERBOSE
diff --git a/src/xml/repr.h b/src/xml/repr.h
index 372a62055..1c3bf1193 100644
--- a/src/xml/repr.h
+++ b/src/xml/repr.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * @brief C facade to Inkscape::XML::Node
  */
@@ -8,9 +9,9 @@
  * Copyright (C) 1999-2002 authors
  * Copyright (C) 2000-2002 Ximian, Inc.
  *
- * Released under GNU GPL, read the file 'COPYING' for more information
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
- 
+
 #ifndef SEEN_SP_REPR_H
 #define SEEN_SP_REPR_H
 
diff --git a/src/xml/simple-document.cpp b/src/xml/simple-document.cpp
index cf7851897..d7a3d84db 100644
--- a/src/xml/simple-document.cpp
+++ b/src/xml/simple-document.cpp
@@ -1,16 +1,13 @@
-/**
- * @file
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
  * Garbage collected XML document implementation.
- */
-/* Copyright 2004-2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2018 Authors
+ * Copyright 2005 MenTaLguY <mental@rydia.net>
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <glib.h> // g_assert()
diff --git a/src/xml/simple-document.h b/src/xml/simple-document.h
index 078fa16a7..2b55a86bc 100644
--- a/src/xml/simple-document.h
+++ b/src/xml/simple-document.h
@@ -1,15 +1,13 @@
-/*
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
  * Inkscape::XML::SimpleDocument - generic XML document implementation
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2018 Authors
  * Copyright 2004-2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
- *
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_SIMPLE_DOCUMENT_H
diff --git a/src/xml/simple-node.cpp b/src/xml/simple-node.cpp
index d076080db..721924a7a 100644
--- a/src/xml/simple-node.cpp
+++ b/src/xml/simple-node.cpp
@@ -1,17 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
- * @brief Garbage collected XML node implementation
- */
-/* Copyright 2003-2005 MenTaLguY <mental@rydia.net>
+ *  Garbage collected XML node implementation
+ *//*
+ * Authors: see git history
+ *
+ * Copyright (C) 2018 Authors
+ * Copyright 2003-2005 MenTaLguY <mental@rydia.net>
  * Copyright 2003 Nathan Hurst
  * Copyright 1999-2003 Lauris Kaplinski
  * Copyright 2000-2002 Ximian Inc.
  *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include <cstring>
diff --git a/src/xml/simple-node.h b/src/xml/simple-node.h
index 97e0b1d89..8d0b25bf5 100644
--- a/src/xml/simple-node.h
+++ b/src/xml/simple-node.h
@@ -1,14 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
- * @brief GC-managed XML node implementation
- */
-/* Copyright 2004-2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
+ * GC-managed XML node implementation
+ *//*
+ * Authors: see git history
  *
- * See the file COPYING for details.
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_NODE_H
diff --git a/src/xml/sp-css-attr.h b/src/xml/sp-css-attr.h
index e3aecf8fa..07db9caa8 100644
--- a/src/xml/sp-css-attr.h
+++ b/src/xml/sp-css-attr.h
@@ -1,15 +1,13 @@
-/*
- * SPCSSAttr - interface for CSS Attributes 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * SPCSSAttr - interface for CSS Attributes
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2010 Authors
  * Copyright 2005 Kees Cook <kees@outflux.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
- *
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_SP_SPCSSATTR_H
diff --git a/src/xml/subtree.cpp b/src/xml/subtree.cpp
index 94c1436a9..5340c2af9 100644
--- a/src/xml/subtree.cpp
+++ b/src/xml/subtree.cpp
@@ -1,15 +1,13 @@
-/*
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
  * XML::Subtree - proxy for an XML subtree
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2018 Authors
  * Copyright 2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
- *
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #include "xml/node.h"
diff --git a/src/xml/subtree.h b/src/xml/subtree.h
index bc6ae913a..ef4002ade 100644
--- a/src/xml/subtree.h
+++ b/src/xml/subtree.h
@@ -1,15 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
  * @brief Object representing a subtree of the XML document
- */
-/* Copyright 2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2015 Authors
+ * Copyright 2005 MenTaLguY <mental@rydia.net>
+ * 
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_SUBTREE_H
diff --git a/src/xml/text-node.h b/src/xml/text-node.h
index ca7880acb..58b12f34d 100644
--- a/src/xml/text-node.h
+++ b/src/xml/text-node.h
@@ -1,15 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /** @file
- * @brief Text node implementation
- */
-/* Copyright 2004-2005 MenTaLguY <mental@rydia.net>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * See the file COPYING for details.
+ * Text node implementation
+ *//*
+ * Authors: see git history
  *
+ * Copyright (C) 2018 Authors
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
  */
 
 #ifndef SEEN_INKSCAPE_XML_TEXT_NODE_H