Index: trunk/src/org/openstreetmap/josm/data/projection/CustomProjection.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/projection/CustomProjection.java	(revision 6852)
+++ trunk/src/org/openstreetmap/josm/data/projection/CustomProjection.java	(revision 6854)
@@ -68,5 +68,6 @@
         no_defs("no_defs", false),
         init("init", true),
-        // JOSM extension, not present in PROJ.4
+        // JOSM extensions, not present in PROJ.4
+        wmssrs("wmssrs", true),
         bounds("bounds", true);
 
@@ -152,4 +153,8 @@
                 this.bounds = parseBounds(s);
             }
+            s = parameters.get(Param.wmssrs.key);
+            if (s != null) {
+                this.code = s;
+            }
         }
     }
@@ -174,5 +179,5 @@
                 if (m.groupCount() >= 3) {
                     value = m.group(3);
-                    // same aliases
+                    // some aliases
                     if (key.equals(Param.proj.key)) {
                         if (value.equals("longlat") || value.equals("latlon") || value.equals("latlong")) {
Index: trunk/src/org/openstreetmap/josm/gui/preferences/projection/CustomProjectionChoice.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/projection/CustomProjectionChoice.java	(revision 6852)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/projection/CustomProjectionChoice.java	(revision 6854)
@@ -188,4 +188,5 @@
             s.append(listKeys(Projections.nadgrids)+"<br>");
             s.append("<b>+bounds=</b>minlon,minlat,maxlon,maxlat - <i>"+tr("Projection bounds (in degrees)")+"</i><br>");
+            s.append("<b>+wmssrs=</b>EPSG:123456 - <i>"+tr("WMS SRS (EPSG code)")+"</i><br>");
 
             return new HtmlPanel(s.toString());