Index: src/path-chemistry.cpp
===================================================================
--- src/path-chemistry.cpp	(revision 21209)
+++ src/path-chemistry.cpp	(working copy)
@@ -518,6 +518,10 @@
     repr->setAttribute("style", style_str);
     g_free(style_str);
 
+    /* Custom attributes */
+    sp_copy_custom_attributes(repr, SP_OBJECT_REPR(item)->attributeList());
+
+
     /* Mask */
     gchar *mask_str = (gchar *) SP_OBJECT_REPR(item)->attribute("mask");
     if ( mask_str )
Index: src/splivarot.cpp
===================================================================
--- src/splivarot.cpp	(revision 21209)
+++ src/splivarot.cpp	(working copy)
@@ -466,6 +466,8 @@
     gchar const *style = repr_source->attribute("style");
     gchar const *mask = repr_source->attribute("mask");
     gchar const *clip_path = repr_source->attribute("clip-path");
+    // remember everything to keep custom attributes
+    Inkscape::Util::List<Inkscape::XML::AttributeRecord const> attrs = repr_source->attributeList();
     gchar *title = source->title();
     gchar *desc = source->desc();
     // remove source paths
@@ -520,6 +522,8 @@
                 repr->setAttribute("mask", mask);
             if (clip_path)
                 repr->setAttribute("clip-path", clip_path);
+ 
+           sp_copy_custom_attributes(repr, attrs);
 
             repr->setAttribute("d", d);
             g_free(d);
@@ -569,6 +573,8 @@
         if ( clip_path )
             repr->setAttribute("clip-path", clip_path);
 
+        sp_copy_custom_attributes(repr, attrs);
+
         repr->setAttribute("d", d);
         g_free(d);
 
@@ -1872,7 +1878,6 @@
     return p;
 }
 
-
 /*
   Local Variables:
   mode:c++
Index: src/xml/repr.h
===================================================================
--- src/xml/repr.h	(revision 21209)
+++ src/xml/repr.h	(working copy)
@@ -37,6 +37,7 @@
 /* SPXMLNs */
 char const *sp_xml_ns_uri_prefix(gchar const *uri, gchar const *suggested);
 char const *sp_xml_ns_prefix_uri(gchar const *prefix);
+bool sp_xml_ns_is_custom(gchar const *prefix);
 
 Inkscape::XML::Document *sp_repr_document_new(gchar const *rootname);
 
@@ -120,7 +121,9 @@
 }
 
 bool sp_repr_is_meta_element(const Inkscape::XML::Node *node);
+void sp_copy_custom_attributes(Inkscape::XML::Node *new_node, Inkscape::Util::List<Inkscape::XML::AttributeRecord const> attrs);
 
+
 /* Convenience */
 unsigned sp_repr_get_boolean(Inkscape::XML::Node *repr, gchar const *key, unsigned *val);
 unsigned sp_repr_get_int(Inkscape::XML::Node *repr, gchar const *key, int *val);
Index: src/xml/repr-util.cpp
===================================================================
--- src/xml/repr-util.cpp	(revision 21209)
+++ src/xml/repr-util.cpp	(working copy)
@@ -35,6 +35,7 @@
 
 #include "xml/repr.h"
 #include "xml/repr-sorting.h"
+#include "xml/attribute-record.h"
 
 
 #define OSB_NS_URI "http://www.openswatchbook.org/uri/2009/osb"
@@ -43,6 +44,7 @@
 struct SPXMLNs {
     SPXMLNs *next;
     unsigned int uri, prefix;
+    bool is_custom;
 };
 
 /*#####################
@@ -157,34 +159,42 @@
 
     defaults[0].uri = g_quark_from_static_string(SP_SODIPODI_NS_URI);
     defaults[0].prefix = g_quark_from_static_string("sodipodi");
+    defaults[0].is_custom = FALSE;
     defaults[0].next = &defaults[1];
 
     defaults[1].uri = g_quark_from_static_string(SP_XLINK_NS_URI);
     defaults[1].prefix = g_quark_from_static_string("xlink");
+    defaults[1].is_custom = FALSE;
     defaults[1].next = &defaults[2];
 
     defaults[2].uri = g_quark_from_static_string(SP_SVG_NS_URI);
     defaults[2].prefix = g_quark_from_static_string("svg");
+    defaults[2].is_custom = FALSE;
     defaults[2].next = &defaults[3];
 
     defaults[3].uri = g_quark_from_static_string(SP_INKSCAPE_NS_URI);
     defaults[3].prefix = g_quark_from_static_string("inkscape");
+    defaults[3].is_custom = FALSE;
     defaults[3].next = &defaults[4];
 
     defaults[4].uri = g_quark_from_static_string(SP_RDF_NS_URI);
     defaults[4].prefix = g_quark_from_static_string("rdf");
+    defaults[4].is_custom = FALSE;
     defaults[4].next = &defaults[5];
 
     defaults[5].uri = g_quark_from_static_string(SP_CC_NS_URI);
     defaults[5].prefix = g_quark_from_static_string("cc");
+    defaults[5].is_custom = FALSE;
     defaults[5].next = &defaults[6];
 
     defaults[6].uri = g_quark_from_static_string(SP_DC_NS_URI);
     defaults[6].prefix = g_quark_from_static_string("dc");
+    defaults[6].is_custom = FALSE;
     defaults[6].next = &defaults[7];
 
     defaults[7].uri = g_quark_from_static_string(OSB_NS_URI);
     defaults[7].prefix = g_quark_from_static_string("osb");
+    defaults[7].is_custom = FALSE;
     defaults[7].next = &defaults[8];
 
     // Inkscape versions prior to 0.44 would write this namespace
@@ -195,6 +205,7 @@
 
     defaults[8].uri = g_quark_from_static_string(SP_BROKEN_SODIPODI_NS_URI);
     defaults[8].prefix = g_quark_from_static_string("sodipodi");
+    defaults[8].is_custom = FALSE;
     defaults[8].next = &defaults[9];
 
     // "Duck prion"
@@ -202,12 +213,14 @@
 
     defaults[9].uri = g_quark_from_static_string("http://inkscape.sourceforge.net/DTD/s odipodi-0.dtd");
     defaults[9].prefix = g_quark_from_static_string("sodipodi");
+    defaults[9].is_custom = FALSE;
     defaults[9].next = &defaults[10];
 
     // This namespace URI is being phased out by Creative Commons
 
     defaults[10].uri = g_quark_from_static_string(SP_OLD_CC_NS_URI);
     defaults[10].prefix = g_quark_from_static_string("cc");
+    defaults[10].is_custom = FALSE;
     defaults[10].next = NULL;
 
     namespaces = &defaults[0];
@@ -240,6 +253,20 @@
     return new_prefix;
 }
 
+bool
+sp_xml_ns_is_custom(gchar const *prefix)
+{
+    SPXMLNs *iter;
+    GQuark const key = g_quark_from_string(prefix);
+    for ( iter = namespaces; iter ; iter = iter->next ) {
+        if ( iter->prefix == key ) {
+            return iter->is_custom;
+        }
+    }
+
+    return TRUE;
+}
+
 gchar const *
 sp_xml_ns_uri_prefix(gchar const *uri, gchar const *suggested)
 {
@@ -284,6 +311,7 @@
         g_assert( ns != NULL );
         ns->uri = g_quark_from_string(uri);
         ns->prefix = g_quark_from_string(new_prefix);
+        ns->is_custom = TRUE;
 
         g_free(new_prefix);
 
@@ -483,7 +511,33 @@
     return false;
 }
 
+
 /**
+ * Copy custom attributes (the ones with a non standart namespace).
+ */
+void sp_copy_custom_attributes(Inkscape::XML::Node *new_node,
+                               Inkscape::Util::List<Inkscape::XML::AttributeRecord const> attrs)
+{
+    // the custom attributes are the ones which have a non standart namespace
+    for ( ; attrs ; attrs++) {
+        const gchar *key = g_quark_to_string(attrs->key);
+        const gchar *prefix_end = strchr(key, ':');
+
+        if ( prefix_end != NULL ) {
+            const gchar *prefix = Glib::ustring(key, prefix_end).data();
+            if ( sp_xml_ns_prefix_uri(prefix) == NULL ) {
+                // unknown prefix
+                new_node->setAttribute(key, attrs->value);
+            } else if ( sp_xml_ns_is_custom(prefix) == TRUE ) {
+                // not a standart one
+                new_node->setAttribute(key, attrs->value);
+            }
+        }
+    }
+}
+
+
+/**
  * Parses the boolean value of an attribute "key" in repr and sets val accordingly, or to FALSE if
  * the attr is not set.
  *