Index: src/org/openstreetmap/josm/gui/MapFrame.java
===================================================================
--- src/org/openstreetmap/josm/gui/MapFrame.java	(revision 275)
+++ src/org/openstreetmap/josm/gui/MapFrame.java	(revision 276)
@@ -66,11 +66,5 @@
 	public final ButtonGroup toolGroup = new ButtonGroup();
 
-	/**
-	 * Construct a map with a given DataSet. The set cannot be replaced after 
-	 * construction (but of course, the data can be altered using the map's
-	 * editing features).
-	 * 
-	 * @param layer The first layer in the mapView. 
-	 */
+
 	public MapFrame() {
 		setSize(400,400);
Index: src/org/openstreetmap/josm/gui/MapView.java
===================================================================
--- src/org/openstreetmap/josm/gui/MapView.java	(revision 275)
+++ src/org/openstreetmap/josm/gui/MapView.java	(revision 276)
@@ -37,6 +37,5 @@
  * what projection the map is viewed etc..
  *
- * MapView is able to administrate several layers, but there must be always at
- * least one layer with a dataset in it (Layer.getDataSet returning non-null).
+ * MapView is able to administrate several layers.
  *
  * @author imi
Index: src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java
===================================================================
--- src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java	(revision 275)
+++ src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java	(revision 276)
@@ -217,4 +217,5 @@
 	/**
 	 * Undoes the last added command.
+	 * TODO: This has to be moved to a central place in order to support multiple layers.
 	 */
 	public void undo() {
@@ -230,4 +231,5 @@
 	/**
 	 * Redoes the last undoed command.
+	 * TODO: This has to be moved to a central place in order to support multiple layers.
 	 */
 	public void redo() {
Index: src/org/openstreetmap/josm/io/OsmReader.java
===================================================================
--- src/org/openstreetmap/josm/io/OsmReader.java	(revision 275)
+++ src/org/openstreetmap/josm/io/OsmReader.java	(revision 276)
@@ -226,4 +226,5 @@
 	    	if (node.id == id)
 	    		return node;
+	    // TODO: This has to be changed to support multiple layers.
 	    for (Node node : Main.ds.nodes)
 	    	if (node.id == id)
@@ -239,4 +240,5 @@
 			if (seg.id == id)
 				return seg;
+		// TODO: This has to be changed to support multiple layers.
 		for (Segment seg : Main.ds.segments)
 			if (seg.id == id)
@@ -270,4 +272,5 @@
 	 * @param ref The dataset that is search in for references first. If
 	 * 	the Reference is not found here, Main.ds is searched.
+	 * TODO: This has to be changed to support multiple layers.
 	 */
 	public static DataSet parseDataSet(InputStream source, DataSet ref, PleaseWaitDialog pleaseWaitDlg) throws SAXException, IOException {