diff --git a/common/dialog_shim.cpp b/common/dialog_shim.cpp
index 5b7b14e39d..12dec84685 100644
--- a/common/dialog_shim.cpp
+++ b/common/dialog_shim.cpp
@@ -162,14 +162,14 @@ void DIALOG_SHIM::setSizeInDU( int x, int y )
 }
 
 
-int DIALOG_SHIM::horizPixelsFromDU( int x )
+int DIALOG_SHIM::horizPixelsFromDU( int x ) const
 {
     wxSize sz( x, 0 );
     return ConvertDialogToPixels( sz ).x;
 }
 
 
-int DIALOG_SHIM::vertPixelsFromDU( int y )
+int DIALOG_SHIM::vertPixelsFromDU( int y ) const
 {
     wxSize sz( 0, y );
     return ConvertDialogToPixels( sz ).y;
diff --git a/common/dialogs/wx_html_report_panel.cpp b/common/dialogs/wx_html_report_panel.cpp
index 9aa2e379cf..d704e6021a 100644
--- a/common/dialogs/wx_html_report_panel.cpp
+++ b/common/dialogs/wx_html_report_panel.cpp
@@ -379,13 +379,13 @@ void WX_HTML_REPORT_PANEL::SetVisibleSeverities( int aSeverities )
 }
 
 
-int WX_HTML_REPORT_PANEL::GetVisibleSeverities()
+int WX_HTML_REPORT_PANEL::GetVisibleSeverities() const
 {
     return m_severities;
 }
 
 
-void WX_HTML_REPORT_PANEL::SetFileName( wxString& aReportFileName )
+void WX_HTML_REPORT_PANEL::SetFileName( const wxString& aReportFileName )
 {
     m_reportFileName = aReportFileName;
 }
diff --git a/common/dialogs/wx_html_report_panel.h b/common/dialogs/wx_html_report_panel.h
index abb66e4fec..325132c597 100644
--- a/common/dialogs/wx_html_report_panel.h
+++ b/common/dialogs/wx_html_report_panel.h
@@ -85,7 +85,7 @@ public:
 
     ///> @return the visible severity filter.
     ///> If the m_showAll option is set, the mask is < 0
-    int GetVisibleSeverities();
+    int GetVisibleSeverities() const;
 
     ///> If true prints Info: at the beginning of each Info severity line (Default)
     void SetPrintInfo( bool aPrintInfo );
@@ -95,7 +95,7 @@ public:
     void SetShowSeverity( SEVERITY aSeverity, bool aValue );
 
     ///> Set the report full file name to the string
-    void SetFileName( wxString& aReportFileName );
+    void SetFileName( const wxString& aReportFileName );
 
     ///> @return reference to the current report fill file name string.
     wxString& GetFileName( void );
diff --git a/common/dsnlexer.cpp b/common/dsnlexer.cpp
index f8703d32f0..f39e0cf026 100644
--- a/common/dsnlexer.cpp
+++ b/common/dsnlexer.cpp
@@ -225,7 +225,7 @@ LINE_READER* DSNLEXER::PopReader()
 }
 
 
-int DSNLEXER::findToken( const std::string& tok )
+int DSNLEXER::findToken( const std::string& tok ) const
 {
     KEYWORD_MAP::const_iterator it = keyword_hash.find( tok.c_str() );
 
@@ -280,7 +280,7 @@ const char* DSNLEXER::Syntax( int aTok )
 }
 
 
-const char* DSNLEXER::GetTokenText( int aTok )
+const char* DSNLEXER::GetTokenText( int aTok ) const
 {
     const char* ret;
 
@@ -299,9 +299,9 @@ const char* DSNLEXER::GetTokenText( int aTok )
 }
 
 
-wxString DSNLEXER::GetTokenString( int aTok )
+wxString DSNLEXER::GetTokenString( int aTok ) const
 {
-    wxString    ret;
+    wxString ret;
 
     ret << wxT("'") << wxString::FromUTF8( GetTokenText(aTok) ) << wxT("'");
 
@@ -314,11 +314,11 @@ bool DSNLEXER::IsSymbol( int aTok )
     // This is static and not inline to reduce code space.
 
     // if aTok is >= 0, then it is a coincidental match to a keyword.
-    return aTok==DSN_SYMBOL || aTok==DSN_STRING || aTok>=0;
+    return aTok == DSN_SYMBOL || aTok == DSN_STRING || aTok >= 0;
 }
 
 
-void DSNLEXER::Expecting( int aTok )
+void DSNLEXER::Expecting( int aTok ) const
 {
     wxString errText = wxString::Format(
         _( "Expecting %s" ), GetTokenString( aTok ) );
@@ -326,7 +326,7 @@ void DSNLEXER::Expecting( int aTok )
 }
 
 
-void DSNLEXER::Expecting( const char* text )
+void DSNLEXER::Expecting( const char* text ) const
 {
     wxString errText = wxString::Format(
         _( "Expecting '%s'" ), wxString::FromUTF8( text ) );
@@ -334,7 +334,7 @@ void DSNLEXER::Expecting( const char* text )
 }
 
 
-void DSNLEXER::Unexpected( int aTok )
+void DSNLEXER::Unexpected( int aTok ) const
 {
     wxString errText = wxString::Format(
         _( "Unexpected %s" ), GetTokenString( aTok ) );
@@ -350,7 +350,7 @@ void DSNLEXER::Duplicate( int aTok )
 }
 
 
-void DSNLEXER::Unexpected( const char* text )
+void DSNLEXER::Unexpected( const char* text ) const
 {
     wxString errText = wxString::Format(
         _( "Unexpected '%s'" ), wxString::FromUTF8( text ) );
diff --git a/common/gbr_metadata.cpp b/common/gbr_metadata.cpp
index d9f56dc6b6..b5a610afba 100644
--- a/common/gbr_metadata.cpp
+++ b/common/gbr_metadata.cpp
@@ -75,7 +75,7 @@ wxString GbrMakeCreationDateAttributeString( GBR_NC_STRING_FORMAT aFormat )
 }
 
 
-wxString GbrMakeProjectGUIDfromString( wxString& aText )
+wxString GbrMakeProjectGUIDfromString( const wxString& aText )
 {
     /* Gerber GUID format should be RFC4122 Version 1 or 4.
      * See en.wikipedia.org/wiki/Universally_unique_identifier
@@ -482,14 +482,14 @@ wxString ConvertNotAllowedCharsInGerber( const wxString& aString, bool aAllowUtf
 }
 
 
-std::string GBR_DATA_FIELD::GetGerberString()
+std::string GBR_DATA_FIELD::GetGerberString() const
 {
     wxString converted;
 
     if( !m_field.IsEmpty() )
         converted = ConvertNotAllowedCharsInGerber( m_field, m_useUTF8, m_escapeString );
 
-    // Convert the char string to std::string. Be carefull when converting awxString to
+    // Convert the char string to std::string. Be carefull when converting a wxString to
     // a std::string: using static_cast<const char*> is mandatory
     std::string txt = static_cast<const char*>( converted.utf8_str() );
 
@@ -525,7 +525,7 @@ std::string FormatStringToGerber( const wxString& aString )
 #define NO_PAD_NAME wxT( "" )       // pad name of pads without pad name/number (not normalized)
 
 bool FormatNetAttribute( std::string& aPrintedText, std::string& aLastNetAttributes,
-                         GBR_NETLIST_METADATA* aData, bool& aClearPreviousAttributes,
+                         const GBR_NETLIST_METADATA* aData, bool& aClearPreviousAttributes,
                          bool aUseX1StructuredComment )
 {
     aClearPreviousAttributes = false;
diff --git a/common/observable.cpp b/common/observable.cpp
index b172a75fc9..1a80ef884a 100644
--- a/common/observable.cpp
+++ b/common/observable.cpp
@@ -32,7 +32,7 @@ namespace UTIL {
         struct equals {
             equals( const T& val ) : val_( val ) {}
 
-            bool operator()( const T& val )
+            bool operator()( const T& val ) const
             {
                 return val == val_;
             }
diff --git a/common/ptree.cpp b/common/ptree.cpp
index 5e6b47c4ac..79fabe78b4 100644
--- a/common/ptree.cpp
+++ b/common/ptree.cpp
@@ -75,7 +75,7 @@ inline void scanList( PTREE* aTree, DSNLEXER* aLexer )
 }
 
 
-inline void scanAtom( PTREE* aTree, DSNLEXER* aLexer )
+inline void scanAtom( PTREE* aTree, const DSNLEXER* aLexer )
 {
     const char* key = aLexer->CurText();
 
@@ -109,13 +109,13 @@ void Scan( PTREE* aTree, DSNLEXER* aLexer )
 
 //-----<Format>------------------------------------------------------------------
 
-inline bool isAtom( CPTREE& aTree )
+inline bool isAtom( const CPTREE& aTree )
 {
-    return aTree.size()==0 && aTree.data().size()==0;
+    return aTree.size() == 0 && aTree.data().size() == 0;
 }
 
 
-inline bool isLast( CPTREE& aTree, CITER it )
+inline bool isLast( const CPTREE& aTree, CITER it )
 {
     CITER next = it;
     ++next;
@@ -131,13 +131,12 @@ inline CITER next( CITER it )
 
 
 static void formatNode( OUTPUTFORMATTER* out, int aNestLevel, int aCtl,
-        const std::string& aKey, CPTREE& aTree );
+        const std::string& aKey, const CPTREE& aTree );
 
 
-static void formatList( OUTPUTFORMATTER* out, int aNestLevel, int aCtl, CPTREE& aTree )
-
+static void formatList( OUTPUTFORMATTER* out, int aNestLevel, int aCtl, const CPTREE& aTree )
 {
-    for( CITER it = aTree.begin();  it != aTree.end();  ++it )
+    for( CITER it = aTree.begin(); it != aTree.end(); ++it )
     {
         // Processing a tree which was read in with xml_parser?
         if( it->first == "<xmlattr>" )
@@ -165,7 +164,7 @@ static void formatList( OUTPUTFORMATTER* out, int aNestLevel, int aCtl, CPTREE&
 
 
 static void formatNode( OUTPUTFORMATTER* out, int aNestLevel, int aCtl,
-        const std::string& aKey, CPTREE& aTree )
+        const std::string& aKey, const CPTREE& aTree )
 
 {
     if( !isAtom( aTree ) )     // is a list, not an atom
@@ -198,7 +197,7 @@ static void formatNode( OUTPUTFORMATTER* out, int aNestLevel, int aCtl,
 }
 
 
-void Format( OUTPUTFORMATTER* out, int aNestLevel, int aCtl, CPTREE& aTree )
+void Format( OUTPUTFORMATTER* out, int aNestLevel, int aCtl, const CPTREE& aTree )
 {
     if( aTree.size() == 1 && !aTree.data().size() )
     {
diff --git a/eeschema/dialogs/dialog_lib_edit_pin_table.cpp b/eeschema/dialogs/dialog_lib_edit_pin_table.cpp
index a33e8438b5..dd9869fd62 100644
--- a/eeschema/dialogs/dialog_lib_edit_pin_table.cpp
+++ b/eeschema/dialogs/dialog_lib_edit_pin_table.cpp
@@ -278,7 +278,7 @@ public:
         return res;
     }
 
-    void RebuildRows( LIB_PINS& aPins, bool groupByName )
+    void RebuildRows( const LIB_PINS& aPins, bool groupByName )
     {
         if ( GetView() )
         {
diff --git a/eeschema/dialogs/dialog_plot_schematic.cpp b/eeschema/dialogs/dialog_plot_schematic.cpp
index 0d05ec2f7b..ab00b05ad6 100644
--- a/eeschema/dialogs/dialog_plot_schematic.cpp
+++ b/eeschema/dialogs/dialog_plot_schematic.cpp
@@ -358,8 +358,8 @@ void DIALOG_PLOT_SCHEMATIC::PlotSchematic( bool aPlotAll )
 }
 
 
-wxFileName DIALOG_PLOT_SCHEMATIC::createPlotFileName( wxString& aPlotFileName,
-                                                      wxString& aExtension,
+wxFileName DIALOG_PLOT_SCHEMATIC::createPlotFileName( const wxString& aPlotFileName,
+                                                      const wxString& aExtension,
                                                       REPORTER* aReporter )
 {
     wxString   path = ExpandEnvVarSubstitutions( m_outputDirectoryName->GetValue(), &Prj() );
diff --git a/eeschema/dialogs/dialog_plot_schematic.h b/eeschema/dialogs/dialog_plot_schematic.h
index 857f569ecf..765030b181 100644
--- a/eeschema/dialogs/dialog_plot_schematic.h
+++ b/eeschema/dialogs/dialog_plot_schematic.h
@@ -148,6 +148,7 @@ private:
      * @return the created file name
      * @throw IO_ERROR on file I/O errors
      */
-    wxFileName createPlotFileName( wxString& aPlotFileName, wxString& aExtension,
+    wxFileName createPlotFileName( const wxString& aPlotFileName,
+                                   const wxString& aExtension,
                                    REPORTER* aReporter = NULL );
 };
diff --git a/eeschema/tools/ee_grid_helper.cpp b/eeschema/tools/ee_grid_helper.cpp
index 2d8d83a54d..87dd556a8b 100644
--- a/eeschema/tools/ee_grid_helper.cpp
+++ b/eeschema/tools/ee_grid_helper.cpp
@@ -174,7 +174,7 @@ VECTOR2I EE_GRID_HELPER::AlignToWire( const VECTOR2I& aPoint, const SEG& aSeg )
     return nearest;
 }
 
-VECTOR2I EE_GRID_HELPER::BestDragOrigin( const VECTOR2I &aMousePos, std::vector<SCH_ITEM*>& aItems )
+VECTOR2I EE_GRID_HELPER::BestDragOrigin( const VECTOR2I &aMousePos, const std::vector<SCH_ITEM*>& aItems )
 {
     clearAnchors();
 
diff --git a/eeschema/tools/ee_grid_helper.h b/eeschema/tools/ee_grid_helper.h
index fb8fe92d40..ee3a7d1613 100644
--- a/eeschema/tools/ee_grid_helper.h
+++ b/eeschema/tools/ee_grid_helper.h
@@ -60,7 +60,7 @@ public:
 
     VECTOR2I AlignToWire( const VECTOR2I& aPoint, const SEG& aSeg );
 
-    VECTOR2I BestDragOrigin( const VECTOR2I& aMousePos, std::vector<SCH_ITEM*>& aItem );
+    VECTOR2I BestDragOrigin( const VECTOR2I& aMousePos, const std::vector<SCH_ITEM*>& aItem );
 
     VECTOR2I BestSnapAnchor( const VECTOR2I& aOrigin, SCH_ITEM* aDraggedItem );
     VECTOR2I BestSnapAnchor( const VECTOR2I& aOrigin, const LSET& aLayers,
diff --git a/gerbview/export_to_pcbnew.cpp b/gerbview/export_to_pcbnew.cpp
index 13847fe386..7fcaccaebd 100644
--- a/gerbview/export_to_pcbnew.cpp
+++ b/gerbview/export_to_pcbnew.cpp
@@ -55,7 +55,7 @@ GBR_TO_PCB_EXPORTER::~GBR_TO_PCB_EXPORTER()
 }
 
 
-bool GBR_TO_PCB_EXPORTER::ExportPcb( LAYER_NUM* aLayerLookUpTable, int aCopperLayers )
+bool GBR_TO_PCB_EXPORTER::ExportPcb( const LAYER_NUM* aLayerLookUpTable, int aCopperLayers )
 {
     LOCALE_IO   toggle;     // toggles on, then off, the C locale.
 
@@ -138,7 +138,7 @@ bool GBR_TO_PCB_EXPORTER::ExportPcb( LAYER_NUM* aLayerLookUpTable, int aCopperLa
 }
 
 
-void GBR_TO_PCB_EXPORTER::export_non_copper_item( GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer )
+void GBR_TO_PCB_EXPORTER::export_non_copper_item( const GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer )
 {
     // used when a D_CODE is not found. default D_CODE to draw a flashed item
     static D_CODE  dummyD_CODE( 0 );
@@ -252,7 +252,7 @@ void GBR_TO_PCB_EXPORTER::export_non_copper_item( GERBER_DRAW_ITEM* aGbrItem, LA
  * the pad gets drawn as a copper polygon, or increase it to the proper size if it has a
  * circular, concentric copper flashing.
  */
-void GBR_TO_PCB_EXPORTER::collect_hole( GERBER_DRAW_ITEM* aGbrItem )
+void GBR_TO_PCB_EXPORTER::collect_hole( const GERBER_DRAW_ITEM* aGbrItem )
 {
     int size = std::min( aGbrItem->m_Size.x, aGbrItem->m_Size.y );
     m_vias.emplace_back( aGbrItem->m_Start, size + 1, size );
@@ -279,7 +279,7 @@ void GBR_TO_PCB_EXPORTER::export_via( const EXPORT_VIA& aVia )
 }
 
 
-void GBR_TO_PCB_EXPORTER::export_copper_item( GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer )
+void GBR_TO_PCB_EXPORTER::export_copper_item( const GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer )
 {
     switch( aGbrItem->m_Shape )
     {
@@ -313,7 +313,7 @@ void GBR_TO_PCB_EXPORTER::export_copper_item( GERBER_DRAW_ITEM* aGbrItem, LAYER_
 }
 
 
-void GBR_TO_PCB_EXPORTER::export_segline_copper_item( GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer )
+void GBR_TO_PCB_EXPORTER::export_segline_copper_item( const GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer )
 {
     wxPoint seg_start, seg_end;
 
@@ -328,7 +328,8 @@ void GBR_TO_PCB_EXPORTER::export_segline_copper_item( GERBER_DRAW_ITEM* aGbrItem
 }
 
 
-void GBR_TO_PCB_EXPORTER::writeCopperLineItem( wxPoint& aStart, wxPoint& aEnd,
+void GBR_TO_PCB_EXPORTER::writeCopperLineItem( const wxPoint& aStart,
+                                               const wxPoint& aEnd,
                                                int aWidth, LAYER_NUM aLayer )
 {
   fprintf( m_fp, "(segment (start %s %s) (end %s %s) (width %s) (layer %s) (net 0))\n",
@@ -341,7 +342,7 @@ void GBR_TO_PCB_EXPORTER::writeCopperLineItem( wxPoint& aStart, wxPoint& aEnd,
 }
 
 
-void GBR_TO_PCB_EXPORTER::export_segarc_copper_item( GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer )
+void GBR_TO_PCB_EXPORTER::export_segarc_copper_item( const GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer )
 {
     double  a = atan2( (double) ( aGbrItem->m_Start.y - aGbrItem->m_ArcCentre.y ),
                        (double) ( aGbrItem->m_Start.x - aGbrItem->m_ArcCentre.x ) );
@@ -402,7 +403,7 @@ void GBR_TO_PCB_EXPORTER::export_segarc_copper_item( GERBER_DRAW_ITEM* aGbrItem,
  * then we'll enlarge the via to the proper size.  Otherwise we create a copper polygon to
  * represent the flashed item (which is presumably a pad).
  */
-void GBR_TO_PCB_EXPORTER::export_flashed_copper_item( GERBER_DRAW_ITEM* aGbrItem,
+void GBR_TO_PCB_EXPORTER::export_flashed_copper_item( const GERBER_DRAW_ITEM* aGbrItem,
                                                       LAYER_NUM aLayer )
 {
     static D_CODE  flashed_item_D_CODE( 0 );
@@ -433,7 +434,7 @@ void GBR_TO_PCB_EXPORTER::export_flashed_copper_item( GERBER_DRAW_ITEM* aGbrItem
 }
 
 
-void GBR_TO_PCB_EXPORTER::writePcbHeader( LAYER_NUM* aLayerLookUpTable )
+void GBR_TO_PCB_EXPORTER::writePcbHeader( const LAYER_NUM* aLayerLookUpTable )
 {
     fprintf( m_fp, "(kicad_pcb (version 4) (host Gerbview \"%s\")\n\n",
              TO_UTF8( GetBuildVersion() ) );
@@ -512,7 +513,7 @@ void GBR_TO_PCB_EXPORTER::writePcbPolygon( const SHAPE_POLY_SET& aPolys, LAYER_N
 }
 
 
-void GBR_TO_PCB_EXPORTER::writePcbZoneItem( GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer )
+void GBR_TO_PCB_EXPORTER::writePcbZoneItem( const GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer )
 {
     SHAPE_POLY_SET polys = aGbrItem->m_Polygon;
     polys.Simplify( SHAPE_POLY_SET::PM_STRICTLY_SIMPLE );
diff --git a/gerbview/export_to_pcbnew.h b/gerbview/export_to_pcbnew.h
index c92d1fa254..c7cb766e39 100644
--- a/gerbview/export_to_pcbnew.h
+++ b/gerbview/export_to_pcbnew.h
@@ -64,7 +64,7 @@ public:
      * Function ExportPcb
      * saves a board from a set of Gerber images.
      */
-    bool    ExportPcb( LAYER_NUM* aLayerLookUpTable, int aCopperLayers );
+    bool    ExportPcb( const LAYER_NUM* aLayerLookUpTable, int aCopperLayers );
 
 private:
     /**
@@ -72,7 +72,7 @@ private:
      * We'll use these later when writing pads & vias.
      * @param aGbrItem
      */
-    void    collect_hole( GERBER_DRAW_ITEM* aGbrItem );
+    void    collect_hole( const GERBER_DRAW_ITEM* aGbrItem );
 
     /**
      * write a via to the board file.
@@ -88,7 +88,7 @@ private:
      * @param aGbrItem = the Gerber item (line, arc) to export
      * @param aLayer = the technical layer to use
      */
-    void    export_non_copper_item( GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
+    void    export_non_copper_item( const GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
 
     /**
      * write a non-copper polygon to the board file.
@@ -103,14 +103,14 @@ private:
      * @param aGbrItem = the Gerber item (line, arc) to export
      * @param aLayer = the technical layer to use
      */
-    void    writePcbZoneItem( GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
+    void    writePcbZoneItem( const GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
 
     /**
      * write a track (or via) to the board file.
      * @param aGbrItem = the Gerber item (line, arc, flashed) to export
      * @param aLayer = the copper layer to use
      */
-    void    export_copper_item( GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
+    void    export_copper_item( const GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
 
     /**
      * Function export_flashed_copper_item
@@ -120,7 +120,7 @@ private:
      * the pad.
      * @param aGbrItem = the flashed Gerber item to export
      */
-    void    export_flashed_copper_item( GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
+    void    export_flashed_copper_item( const GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
 
     /**
      * Function export_segline_copper_item
@@ -128,7 +128,7 @@ private:
      * @param aGbrItem = the Gerber item (line only) to export
      * @param aLayer = the copper layer to use
      */
-    void    export_segline_copper_item( GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
+    void    export_segline_copper_item( const GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
 
     /**
      * Function export_segarc_copper_item
@@ -137,27 +137,28 @@ private:
      * @param aGbrItem = the Gerber item (arc only) to export
      * @param aLayer = the copper layer to use
      */
-    void    export_segarc_copper_item( GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
+    void    export_segarc_copper_item( const GERBER_DRAW_ITEM* aGbrItem, LAYER_NUM aLayer );
 
     /**
      * function writeCopperLineItem
      * basic write function to write a a TRACK item
      * to the board file, from a non flashed item
      */
-    void    writeCopperLineItem( wxPoint& aStart, wxPoint& aEnd,
+    void    writeCopperLineItem( const wxPoint& aStart,
+                                 const wxPoint& aEnd,
                                  int aWidth, LAYER_NUM aLayer );
 
     /**
      * function writePcbHeader
      * Write a very basic header to the board file
      */
-    void    writePcbHeader( LAYER_NUM* aLayerLookUpTable );
+    void    writePcbHeader( const LAYER_NUM* aLayerLookUpTable );
 
     /** In Pcbnew files units are mm for coordinates.
      * So MapToPcbUnits converts internal gerbview to mm any pcbnew value
      * @param aValue is a coordinate value to convert in mm
      */
-    double MapToPcbUnits( int aValue )
+    double MapToPcbUnits( int aValue ) const
     {
         return aValue / IU_PER_MM;
     }
diff --git a/include/dialog_shim.h b/include/dialog_shim.h
index f713fbb5d0..a08d72bd72 100644
--- a/include/dialog_shim.h
+++ b/include/dialog_shim.h
@@ -120,7 +120,7 @@ public:
 
     void EndQuasiModal( int retCode );  // End quasi-modal mode
 
-    bool IsQuasiModal()         { return m_qmodal_showing; }
+    bool IsQuasiModal() const { return m_qmodal_showing; }
 
     bool Show( bool show ) override;
 
@@ -170,13 +170,13 @@ protected:
      * Convert an integer number of dialog units to pixels, horizontally. See SetSizeInDU or
      * wxDialog documentation for more information.
      */
-    int horizPixelsFromDU( int x );
+    int horizPixelsFromDU( int x ) const;
 
     /**
      * Convert an integer number of dialog units to pixels, vertically. See SetSizeInDU or
      * wxDialog documentation for more information.
      */
-    int vertPixelsFromDU( int y );
+    int vertPixelsFromDU( int y ) const;
 
     /**
      * Clear the existing dialog size and position.
diff --git a/include/dsnlexer.h b/include/dsnlexer.h
index a553dacd6c..d16e2c92ae 100644
--- a/include/dsnlexer.h
+++ b/include/dsnlexer.h
@@ -42,7 +42,7 @@ struct KEYWORD
     const char* name;       ///< unique keyword.
     int         token;      ///< a zero based index into an array of KEYWORDs
 };
-#endif
+#endif // SWIG
 
 // something like this macro can be used to help initialize a KEYWORD table.
 // see SPECCTRA_DB::keywords[] as an example.
@@ -55,18 +55,19 @@ struct KEYWORD
  * lists all the DSN lexer's tokens that are supported in lexing.  It is up
  * to the parser if it wants also to support them.
  */
-enum DSN_SYNTAX_T {
-    DSN_NONE = -11,
-    DSN_COMMENT = -10,
+enum DSN_SYNTAX_T
+{
+    DSN_NONE         = -11,
+    DSN_COMMENT      = -10,
     DSN_STRING_QUOTE = -9,
-    DSN_QUOTE_DEF = -8,
-    DSN_DASH = -7,
-    DSN_SYMBOL = -6,
-    DSN_NUMBER = -5,
-    DSN_RIGHT = -4,           // right bracket, ')'
-    DSN_LEFT = -3,            // left bracket, '('
-    DSN_STRING = -2,          // a quoted string, stripped of the quotes
-    DSN_EOF = -1              // special case for end of file
+    DSN_QUOTE_DEF    = -8,
+    DSN_DASH         = -7,
+    DSN_SYMBOL       = -6,
+    DSN_NUMBER       = -5,
+    DSN_RIGHT        = -4,  // right bracket, ')'
+    DSN_LEFT         = -3,  // left bracket, '('
+    DSN_STRING       = -2,  // a quoted string, stripped of the quotes
+    DSN_EOF          = -1   // special case for end of file
 };
 
 
@@ -142,11 +143,11 @@ protected:
      * @return int - with a value from the enum DSN_T matching the keyword text,
      *         or DSN_SYMBOL if @a aToken is not in the kewords table.
      */
-    int findToken( const std::string& aToken );
+    int findToken( const std::string& aToken ) const;
 
-    bool isStringTerminator( char cc )
+    bool isStringTerminator( char cc ) const
     {
-        if( !space_in_quoted_tokens && cc==' ' )
+        if( !space_in_quoted_tokens && cc == ' ' )
             return true;
 
         if( cc == stringDelimiter )
@@ -155,7 +156,7 @@ protected:
         return false;
     }
 
-#endif
+#endif // SWIG
 
 public:
 
@@ -317,7 +318,7 @@ public:
      * Function CurTok
      * returns whatever NextTok() returned the last time it was called.
      */
-    int CurTok()
+    int CurTok() const
     {
         return curTok;
     }
@@ -326,7 +327,7 @@ public:
      * Function PrevTok
      * returns whatever NextTok() returned the 2nd to last time it was called.
      */
-    int PrevTok()
+    int PrevTok() const
     {
         return prevTok;
     }
@@ -335,7 +336,7 @@ public:
      * Function GetCurStrAsToken
      * Used to support "loose" matches (quoted tokens)
      */
-    int GetCurStrAsToken()
+    int GetCurStrAsToken() const
     {
         return findToken( curText );
     }
@@ -412,7 +413,7 @@ public:
      * @param aTok is the token/keyword type which was expected at the current input location.
      * @throw IO_ERROR with the location within the input file of the problem.
      */
-    void Expecting( int aTok );
+    void Expecting( int aTok ) const;
 
     /**
      * Function Expecting
@@ -421,7 +422,7 @@ public:
      *         current input location, e.g.  "pin|graphic|property"
      * @throw IO_ERROR with the location within the input file of the problem.
      */
-    void Expecting( const char* aTokenList );
+    void Expecting( const char* aTokenList ) const;
 
     /**
      * Function Unexpected
@@ -430,7 +431,7 @@ public:
      *         current input location.
      * @throw IO_ERROR with the location within the input file of the problem.
      */
-    void Unexpected( int aTok );
+    void Unexpected( int aTok ) const;
 
     /**
      * Function Unexpected
@@ -439,7 +440,7 @@ public:
      *         current input location.
      * @throw IO_ERROR with the location within the input file of the problem.
      */
-    void Unexpected( const char* aToken );
+    void Unexpected( const char* aToken ) const;
 
     /**
      * Function Duplicate
@@ -471,13 +472,13 @@ public:
      * Function GetTokenText
      * returns the C string representation of a DSN_T value.
      */
-    const char* GetTokenText( int aTok );
+    const char* GetTokenText( int aTok ) const;
 
     /**
      * Function GetTokenString
      * returns a quote wrapped wxString representation of a token value.
      */
-    wxString GetTokenString( int aTok );
+    wxString GetTokenString( int aTok ) const;
 
     static const char* Syntax( int aTok );
 
@@ -485,7 +486,7 @@ public:
      * Function CurText
      * returns a pointer to the current token's text.
      */
-    const char* CurText()
+    const char* CurText() const
     {
         return curText.c_str();
     }
@@ -494,7 +495,7 @@ public:
      * Function CurStr
      * returns a reference to current token in std::string form.
      */
-    const std::string& CurStr()
+    const std::string& CurStr() const
     {
         return curText;
     }
@@ -504,7 +505,7 @@ public:
      * returns the current token text as a wxString, assuming that the input
      * byte stream is UTF8 encoded.
      */
-    wxString FromUTF8()
+    wxString FromUTF8() const
     {
         return wxString::FromUTF8( curText.c_str() );
     }
@@ -513,7 +514,7 @@ public:
      * Function CurLineNumber
      * returns the current line number within my LINE_READER
      */
-    int CurLineNumber()
+    int CurLineNumber() const
     {
         return reader->LineNumber();
     }
@@ -523,7 +524,7 @@ public:
      * returns the current line of text, from which the CurText() would return
      * its token.
      */
-    const char* CurLine()
+    const char* CurLine() const
     {
         return (const char*)(*reader);
     }
@@ -534,7 +535,7 @@ public:
      * @return const wxString& - the source of the lines of text,
      *   e.g. a filename or "clipboard".
      */
-    const wxString& CurSource()
+    const wxString& CurSource() const
     {
         return reader->GetSource();
     }
@@ -544,7 +545,7 @@ public:
      * returns the byte offset within the current line, using a 1 based index.
      * @return int - a one based index into the current line.
      */
-    int CurOffset()
+    int CurOffset() const
     {
         return curOffset + 1;
     }
diff --git a/include/gbr_metadata.h b/include/gbr_metadata.h
index 10671f8388..c289c6e052 100644
--- a/include/gbr_metadata.h
+++ b/include/gbr_metadata.h
@@ -66,7 +66,7 @@ wxString GbrMakeCreationDateAttributeString( GBR_NC_STRING_FORMAT aFormat );
  *
  * See en.wikipedia.org/wiki/Universally_unique_identifier
  */
-wxString GbrMakeProjectGUIDfromString( wxString& aText );
+wxString GbrMakeProjectGUIDfromString( const wxString& aText );
 
 
 // this class handle info which can be added in a gerber file as attribute
@@ -272,7 +272,7 @@ wxString FormatStringFromGerber( const wxString& aString );
  * will be empty
  */
 bool FormatNetAttribute( std::string& aPrintedText, std::string& aLastNetAttributes,
-                         GBR_NETLIST_METADATA* aData, bool& aClearPreviousAttributes,
+                         const GBR_NETLIST_METADATA* aData, bool& aClearPreviousAttributes,
                          bool aUseX1StructuredComment );
 
 #endif      // GBR_METADATA_H
diff --git a/include/gbr_netlist_metadata.h b/include/gbr_netlist_metadata.h
index ce82d8be26..623946cace 100644
--- a/include/gbr_netlist_metadata.h
+++ b/include/gbr_netlist_metadata.h
@@ -118,7 +118,7 @@ public:
 
     bool IsEmpty() const { return m_field.IsEmpty(); }
 
-    std::string GetGerberString();
+    std::string GetGerberString() const;
 
 
 private:
diff --git a/include/kiway_holder.h b/include/kiway_holder.h
index 7755ccdc7b..202ff25aa4 100644
--- a/include/kiway_holder.h
+++ b/include/kiway_holder.h
@@ -46,7 +46,7 @@ public:
         m_type( aType )
     {}
 
-    HOLDER_TYPE GetType() { return m_type; }
+    HOLDER_TYPE GetType() const { return m_type; }
     
     /**
      * Function Kiway
diff --git a/include/ptree.h b/include/ptree.h
index 494b216c56..d3fbd23295 100644
--- a/include/ptree.h
+++ b/include/ptree.h
@@ -90,6 +90,6 @@ void Scan( PTREE* aTree, DSNLEXER* aLexer );
  * Function Format
  * outputs a PTREE into s-expression format via an OUTPUTFORMATTER derivative.
  */
-void Format( OUTPUTFORMATTER* out, int aNestLevel, int aCtl, CPTREE& aTree );
+void Format( OUTPUTFORMATTER* out, int aNestLevel, int aCtl, const CPTREE& aTree );
 
 #endif  // PTREE_H_
diff --git a/libs/kimath/include/geometry/shape_file_io.h b/libs/kimath/include/geometry/shape_file_io.h
index 46930d8ab8..7392ffcf58 100644
--- a/libs/kimath/include/geometry/shape_file_io.h
+++ b/libs/kimath/include/geometry/shape_file_io.h
@@ -57,7 +57,7 @@ class SHAPE_FILE_IO
 
         void Write( const SHAPE* aShape, const std::string& aName = "<noname>" );
 
-        void Write( const SHAPE& aShape, const std::string aName = "<noname>" )
+        void Write( const SHAPE& aShape, const std::string& aName = "<noname>" )
         {
             Write( &aShape, aName );
         }
@@ -68,4 +68,4 @@ class SHAPE_FILE_IO
         IO_MODE m_mode;
 };
 
-#endif
+#endif // __SHAPE_FILE_IO_H
diff --git a/libs/kimath/src/geometry/shape_line_chain.cpp b/libs/kimath/src/geometry/shape_line_chain.cpp
index e36f3f361d..034a8405f2 100644
--- a/libs/kimath/src/geometry/shape_line_chain.cpp
+++ b/libs/kimath/src/geometry/shape_line_chain.cpp
@@ -534,11 +534,11 @@ void SHAPE_LINE_CHAIN::Insert( size_t aVertex, const SHAPE_ARC& aArc )
 
 struct compareOriginDistance
 {
-    compareOriginDistance( VECTOR2I& aOrigin ) :
+    compareOriginDistance( const VECTOR2I& aOrigin ) :
         m_origin( aOrigin ) {};
 
     bool operator()( const SHAPE_LINE_CHAIN::INTERSECTION& aA,
-                     const SHAPE_LINE_CHAIN::INTERSECTION& aB )
+                     const SHAPE_LINE_CHAIN::INTERSECTION& aB ) const
     {
         return ( m_origin - aA.p ).EuclideanNorm() < ( m_origin - aB.p ).EuclideanNorm();
     }
diff --git a/pcbnew/board_stackup_manager/class_board_stackup.cpp b/pcbnew/board_stackup_manager/class_board_stackup.cpp
index cfa294b5e1..ef0c08c3d4 100644
--- a/pcbnew/board_stackup_manager/class_board_stackup.cpp
+++ b/pcbnew/board_stackup_manager/class_board_stackup.cpp
@@ -78,7 +78,7 @@ BOARD_STACKUP_ITEM::BOARD_STACKUP_ITEM( BOARD_STACKUP_ITEM_TYPE aType )
 }
 
 
-BOARD_STACKUP_ITEM::BOARD_STACKUP_ITEM( BOARD_STACKUP_ITEM& aOther )
+BOARD_STACKUP_ITEM::BOARD_STACKUP_ITEM( const BOARD_STACKUP_ITEM& aOther )
 {
     m_LayerId = aOther.m_LayerId;
     m_DielectricLayerId = aOther.m_DielectricLayerId;
@@ -320,7 +320,7 @@ BOARD_STACKUP::BOARD_STACKUP()
 }
 
 
-BOARD_STACKUP::BOARD_STACKUP( BOARD_STACKUP& aOther )
+BOARD_STACKUP::BOARD_STACKUP( const BOARD_STACKUP& aOther )
 {
     m_HasDielectricConstrains  = aOther.m_HasDielectricConstrains;
     m_HasThicknessConstrains   = aOther.m_HasThicknessConstrains;
diff --git a/pcbnew/board_stackup_manager/class_board_stackup.h b/pcbnew/board_stackup_manager/class_board_stackup.h
index 6a7590f4d7..eccf0a3eaa 100644
--- a/pcbnew/board_stackup_manager/class_board_stackup.h
+++ b/pcbnew/board_stackup_manager/class_board_stackup.h
@@ -89,7 +89,7 @@ class BOARD_STACKUP_ITEM
 {
 public:
     BOARD_STACKUP_ITEM( BOARD_STACKUP_ITEM_TYPE aType );
-    BOARD_STACKUP_ITEM( BOARD_STACKUP_ITEM& aOther );
+    BOARD_STACKUP_ITEM( const BOARD_STACKUP_ITEM& aOther );
 
 
 private:
@@ -243,7 +243,7 @@ public:
 
 public:
     BOARD_STACKUP();
-    BOARD_STACKUP( BOARD_STACKUP& aOther );
+    BOARD_STACKUP( const BOARD_STACKUP& aOther );
     BOARD_STACKUP& operator=( const BOARD_STACKUP& aOther );
 
     ~BOARD_STACKUP() { RemoveAll(); }
@@ -267,7 +267,7 @@ public:
     void RemoveAll();
 
     /// @return the number of layers in the stackup
-    int GetCount() { return (int) m_list.size(); }
+    int GetCount() const { return (int) m_list.size(); }
 
     /// @return the board thickness ( in UI) from the thickness of BOARD_STACKUP_ITEM list
     int BuildBoardTicknessFromStackup() const;
@@ -306,4 +306,4 @@ public:
 };
 
 
-#endif      // #ifndef CLASS_BOARD_STACKUP_H
+#endif      // CLASS_BOARD_STACKUP_H
diff --git a/pcbnew/dialogs/dialog_board_reannotate.cpp b/pcbnew/dialogs/dialog_board_reannotate.cpp
index 36cbaef9bb..9104462f62 100644
--- a/pcbnew/dialogs/dialog_board_reannotate.cpp
+++ b/pcbnew/dialogs/dialog_board_reannotate.cpp
@@ -556,8 +556,8 @@ void DIALOG_BOARD_REANNOTATE::LogChangePlan()
 
 //
 /// Create a list of the footprints and their coordinates
-void DIALOG_BOARD_REANNOTATE::LogFootprints( wxString& aMessage,
-                                             std::vector<RefDesInfo>& aFootprints )
+void DIALOG_BOARD_REANNOTATE::LogFootprints( const wxString& aMessage,
+                                             const std::vector<RefDesInfo>& aFootprints )
 {
     wxString message = aMessage;
 
diff --git a/pcbnew/dialogs/dialog_board_reannotate.h b/pcbnew/dialogs/dialog_board_reannotate.h
index f67473fe85..f3fc563a5b 100644
--- a/pcbnew/dialogs/dialog_board_reannotate.h
+++ b/pcbnew/dialogs/dialog_board_reannotate.h
@@ -172,7 +172,7 @@ private:
     void FilterBackPrefix( wxCommandEvent& event ) override;
 
     void ShowReport( wxString aMessage, SEVERITY aSeverity );
-    void LogFootprints( wxString& aMessage, std::vector<RefDesInfo>& aFootprints );
+    void LogFootprints( const wxString& aMessage, const std::vector<RefDesInfo>& aFootprints );
     void LogChangePlan( void );
 
     bool ReannotateBoard( void );
diff --git a/pcbnew/dialogs/dialog_pad_basicshapes_properties.cpp b/pcbnew/dialogs/dialog_pad_basicshapes_properties.cpp
index 67fcb20d45..d2269998f8 100644
--- a/pcbnew/dialogs/dialog_pad_basicshapes_properties.cpp
+++ b/pcbnew/dialogs/dialog_pad_basicshapes_properties.cpp
@@ -559,7 +559,7 @@ DIALOG_PAD_PRIMITIVES_TRANSFORM::DIALOG_PAD_PRIMITIVES_TRANSFORM( wxWindow* aPar
 
 
 // A helper function in geometry transform
-inline void geom_transf( wxPoint& aCoord, wxPoint& aMove, double aScale, double aRotation )
+inline void geom_transf( wxPoint& aCoord, const wxPoint& aMove, double aScale, double aRotation )
 {
     aCoord.x = KiROUND( aCoord.x * aScale );
     aCoord.y = KiROUND( aCoord.y * aScale );
diff --git a/pcbnew/exporters/export_vrml.cpp b/pcbnew/exporters/export_vrml.cpp
index 02d97eba64..ddf0c55986 100644
--- a/pcbnew/exporters/export_vrml.cpp
+++ b/pcbnew/exporters/export_vrml.cpp
@@ -300,7 +300,7 @@ static void create_vrml_shell( IFSG_TRANSFORM& PcbOutput, VRML_COLOR_INDEX color
 static void create_vrml_plane( IFSG_TRANSFORM& PcbOutput, VRML_COLOR_INDEX colorID,
                                VRML_LAYER* layer, double aHeight, bool aTopPlane );
 
-static void write_triangle_bag( std::ostream& aOut_file, VRML_COLOR& aColor,
+static void write_triangle_bag( std::ostream& aOut_file, const VRML_COLOR& aColor,
                                 VRML_LAYER* aLayer, bool aPlane, bool aTop,
                                 double aTop_z, double aBottom_z )
 {
diff --git a/pcbnew/plugins/pcad/pcb.cpp b/pcbnew/plugins/pcad/pcb.cpp
index 05c347558f..5ab1bef949 100644
--- a/pcbnew/plugins/pcad/pcb.cpp
+++ b/pcbnew/plugins/pcad/pcb.cpp
@@ -41,7 +41,7 @@
 
 namespace PCAD2KICAD {
 
-PCB_LAYER_ID PCB::GetKiCadLayer( int aPCadLayer )
+PCB_LAYER_ID PCB::GetKiCadLayer( int aPCadLayer ) const
 {
     auto it = m_LayersMap.find( aPCadLayer );
 
@@ -51,7 +51,7 @@ PCB_LAYER_ID PCB::GetKiCadLayer( int aPCadLayer )
     return it->second.KiCadLayer;
 }
 
-LAYER_TYPE_T PCB::GetLayerType( int aPCadLayer )
+LAYER_TYPE_T PCB::GetLayerType( int aPCadLayer ) const
 {
     auto it = m_LayersMap.find( aPCadLayer );
 
@@ -61,7 +61,7 @@ LAYER_TYPE_T PCB::GetLayerType( int aPCadLayer )
     return it->second.layerType;
 }
 
-wxString PCB::GetLayerNetNameRef( int aPCadLayer )
+wxString PCB::GetLayerNetNameRef( int aPCadLayer ) const
 {
     auto it = m_LayersMap.find( aPCadLayer );
 
@@ -117,9 +117,9 @@ PCB::~PCB()
 }
 
 
-int PCB::GetNetCode( wxString aNetName )
+int PCB::GetNetCode( const wxString& aNetName ) const
 {
-    PCB_NET* net;
+    const PCB_NET* net;
 
     for( int i = 0; i < (int) m_PcbNetlist.GetCount(); i++ )
     {
@@ -134,7 +134,7 @@ int PCB::GetNetCode( wxString aNetName )
     return 0;
 }
 
-XNODE* PCB::FindCompDefName( XNODE* aNode, const wxString& aName )
+XNODE* PCB::FindCompDefName( XNODE* aNode, const wxString& aName ) const
 {
     XNODE*      result = NULL, * lNode;
     wxString    propValue;
@@ -449,7 +449,7 @@ void PCB::ConnectPinToNet( const wxString& aCompRef, const wxString& aPinRef,
 }
 
 
-int PCB::FindLayer( const wxString& aLayerName )
+int PCB::FindLayer( const wxString& aLayerName ) const
 {
     for( LAYER_NUM i = 0; i < (int)m_layersStackup.GetCount(); ++i )
     {
@@ -554,7 +554,7 @@ void PCB::MapLayer( XNODE* aNode )
     }
 }
 
-int PCB::FindOutlinePoint( VERTICES_ARRAY* aOutline, wxRealPoint aPoint )
+int PCB::FindOutlinePoint( const VERTICES_ARRAY* aOutline, wxRealPoint aPoint ) const
 {
     int i;
 
@@ -572,7 +572,7 @@ int PCB::FindOutlinePoint( VERTICES_ARRAY* aOutline, wxRealPoint aPoint )
 
     return 0;
 }*/
-double PCB::GetDistance( wxRealPoint* aPoint1, wxRealPoint* aPoint2 )
+double PCB::GetDistance( const wxRealPoint* aPoint1, const wxRealPoint* aPoint2 ) const
 {
     return sqrt(  ( aPoint1->x - aPoint2->x ) *
                   ( aPoint1->x - aPoint2->x ) +
diff --git a/pcbnew/plugins/pcad/pcb.h b/pcbnew/plugins/pcad/pcb.h
index cfaf2d4bd9..761ab26834 100644
--- a/pcbnew/plugins/pcad/pcb.h
+++ b/pcbnew/plugins/pcad/pcb.h
@@ -52,10 +52,10 @@ public:
     PCB( BOARD* aBoard );
     ~PCB();
 
-    PCB_LAYER_ID GetKiCadLayer( int aPCadLayer ) override;
-    LAYER_TYPE_T GetLayerType( int aPCadLayer ) override;
-    wxString GetLayerNetNameRef( int aPCadLayer ) override;
-    int GetNetCode( wxString aNetName ) override;
+    PCB_LAYER_ID GetKiCadLayer( int aPCadLayer ) const override;
+    LAYER_TYPE_T GetLayerType( int aPCadLayer ) const override;
+    wxString GetLayerNetNameRef( int aPCadLayer ) const override;
+    int GetNetCode( const wxString& aNetName ) const override;
 
     void ParseBoard( wxStatusBar* aStatusBar, wxXmlDocument* aXmlDoc,
                      const wxString& aActualConversion );
@@ -65,20 +65,20 @@ public:
 private:
     wxArrayString   m_layersStackup;
 
-    XNODE* FindCompDefName( XNODE* aNode, const wxString& aName );
+    XNODE* FindCompDefName( XNODE* aNode, const wxString& aName ) const;
 
     void SetTextProperty( XNODE* aNode, TTEXTVALUE* aTextValue, const wxString& aPatGraphRefName,
                           const wxString& aXmlName, const wxString& aActualConversion );
 
-    void DoPCBComponents( XNODE* aNode, wxXmlDocument*  aXmlDoc, const wxString& aActualConversion,
+    void DoPCBComponents( XNODE* aNode, wxXmlDocument* aXmlDoc, const wxString& aActualConversion,
                           wxStatusBar* aStatusBar );
 
     void ConnectPinToNet( const wxString& aCr, const wxString& aPr, const wxString& aNetName );
 
-    int FindLayer( const wxString& aLayerName );
+    int FindLayer( const wxString& aLayerName ) const;
     void MapLayer( XNODE* aNode );
-    int FindOutlinePoint( VERTICES_ARRAY* aOutline, wxRealPoint aPoint );
-    double GetDistance( wxRealPoint* aPoint1, wxRealPoint* aPoint2 );
+    int FindOutlinePoint( const VERTICES_ARRAY* aOutline, wxRealPoint aPoint ) const;
+    double GetDistance( const wxRealPoint* aPoint1, const wxRealPoint* aPoint2 ) const;
     void GetBoardOutline( wxXmlDocument* aXmlDoc, const wxString& aActualConversion );
 };
 
diff --git a/pcbnew/plugins/pcad/pcb_callbacks.h b/pcbnew/plugins/pcad/pcb_callbacks.h
index 31616cc179..f5ddb9bed9 100644
--- a/pcbnew/plugins/pcad/pcb_callbacks.h
+++ b/pcbnew/plugins/pcad/pcb_callbacks.h
@@ -57,10 +57,10 @@ namespace PCAD2KICAD
         {
         }
 
-        virtual PCB_LAYER_ID  GetKiCadLayer( int aPCadLayer ) = 0;
-        virtual LAYER_TYPE_T  GetLayerType( int aPCadLayer ) = 0;
-        virtual wxString      GetLayerNetNameRef( int aPCadLayer ) = 0;
-        virtual int           GetNetCode( wxString netName ) = 0;
+        virtual PCB_LAYER_ID  GetKiCadLayer( int aPCadLayer ) const = 0;
+        virtual LAYER_TYPE_T  GetLayerType( int aPCadLayer ) const = 0;
+        virtual wxString      GetLayerNetNameRef( int aPCadLayer ) const = 0;
+        virtual int           GetNetCode( const wxString& netName ) const = 0;
     };
 }
 
diff --git a/pcbnew/plugins/pcad/pcb_component.h b/pcbnew/plugins/pcad/pcb_component.h
index d072b684f3..fa509b0fae 100644
--- a/pcbnew/plugins/pcad/pcb_component.h
+++ b/pcbnew/plugins/pcad/pcb_component.h
@@ -67,8 +67,8 @@ public:
     virtual void    AddToFootprint( FOOTPRINT* aFootprint );
     virtual void    AddToBoard() = 0;
 
-    PCB_LAYER_ID        GetKiCadLayer() { return m_callbacks->GetKiCadLayer( m_PCadLayer ); }
-    int GetNetCode( wxString aNetName ) { return m_callbacks->GetNetCode( aNetName ); }
+    PCB_LAYER_ID        GetKiCadLayer() const { return m_callbacks->GetKiCadLayer( m_PCadLayer ); }
+    int GetNetCode( wxString aNetName ) const { return m_callbacks->GetNetCode( aNetName ); }
 
 protected:
     PCB_CALLBACKS*  m_callbacks;
diff --git a/pcbnew/router/pns_diff_pair.h b/pcbnew/router/pns_diff_pair.h
index faf2e5c2b3..2c4995bdcb 100644
--- a/pcbnew/router/pns_diff_pair.h
+++ b/pcbnew/router/pns_diff_pair.h
@@ -497,7 +497,7 @@ public:
     }
 
 private:
-    void updateLine( LINE &aLine, const SHAPE_LINE_CHAIN& aShape, int aNet, VIA& aVia )
+    void updateLine( LINE &aLine, const SHAPE_LINE_CHAIN& aShape, int aNet, const VIA& aVia )
     {
         aLine.SetShape( aShape );
         aLine.SetWidth( m_width );
diff --git a/pcbnew/router/pns_node.cpp b/pcbnew/router/pns_node.cpp
index bb353c6710..d240620fb3 100644
--- a/pcbnew/router/pns_node.cpp
+++ b/pcbnew/router/pns_node.cpp
@@ -994,7 +994,7 @@ void NODE::MapConnectivity( JOINT* aStart, std::vector<JOINT*>& aFoundJoints )
 #endif
 
 
-int NODE::FindLinesBetweenJoints( JOINT& aA, JOINT& aB, std::vector<LINE>& aLines )
+int NODE::FindLinesBetweenJoints( const JOINT& aA, const JOINT& aB, std::vector<LINE>& aLines )
 {
     for( ITEM* item : aA.LinkList() )
     {
diff --git a/pcbnew/router/pns_node.h b/pcbnew/router/pns_node.h
index 1df13c3e7f..d476b371a4 100644
--- a/pcbnew/router/pns_node.h
+++ b/pcbnew/router/pns_node.h
@@ -425,8 +425,8 @@ public:
 #endif
 
     ///> finds all lines between a pair of joints. Used by the loop removal procedure.
-    int FindLinesBetweenJoints( JOINT&                  aA,
-                                JOINT&                  aB,
+    int FindLinesBetweenJoints( const JOINT&            aA,
+                                const JOINT&            aB,
                                 std::vector<LINE>&      aLines );
 
     ///> finds the joints corresponding to the ends of line aLine
diff --git a/pcbnew/router/pns_optimizer.cpp b/pcbnew/router/pns_optimizer.cpp
index ea97a919b0..cc4cc80d91 100644
--- a/pcbnew/router/pns_optimizer.cpp
+++ b/pcbnew/router/pns_optimizer.cpp
@@ -89,21 +89,21 @@ int COST_ESTIMATOR::CornerCost( const LINE& aLine )
 }
 
 
-void COST_ESTIMATOR::Add( LINE& aLine )
+void COST_ESTIMATOR::Add( const LINE& aLine )
 {
     m_lengthCost += aLine.CLine().Length();
     m_cornerCost += CornerCost( aLine );
 }
 
 
-void COST_ESTIMATOR::Remove( LINE& aLine )
+void COST_ESTIMATOR::Remove( const LINE& aLine )
 {
     m_lengthCost -= aLine.CLine().Length();
     m_cornerCost -= CornerCost( aLine );
 }
 
 
-void COST_ESTIMATOR::Replace( LINE& aOldLine, LINE& aNewLine )
+void COST_ESTIMATOR::Replace( const LINE& aOldLine, const LINE& aNewLine )
 {
     m_lengthCost -= aOldLine.CLine().Length();
     m_cornerCost -= CornerCost( aOldLine );
@@ -112,7 +112,7 @@ void COST_ESTIMATOR::Replace( LINE& aOldLine, LINE& aNewLine )
 }
 
 
-bool COST_ESTIMATOR::IsBetter( COST_ESTIMATOR& aOther,
+bool COST_ESTIMATOR::IsBetter( const COST_ESTIMATOR& aOther,
         double aLengthTolerance,
         double aCornerTolerance ) const
 {
@@ -216,7 +216,7 @@ void OPTIMIZER::CacheStaticItem( ITEM* aItem )
 }
 
 
-void OPTIMIZER::ClearCache( bool aStaticOnly  )
+void OPTIMIZER::ClearCache( bool aStaticOnly )
 {
     if( !aStaticOnly )
     {
@@ -236,7 +236,7 @@ void OPTIMIZER::ClearCache( bool aStaticOnly  )
 }
 
 
-bool ANGLE_CONSTRAINT_45::Check ( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
+bool ANGLE_CONSTRAINT_45::Check( int aVertex1, int aVertex2, const LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
 {
     auto dir_orig0 = DIRECTION_45( aOriginLine->CSegment( aVertex1 ) );
     auto dir_orig1 = DIRECTION_45( aOriginLine->CSegment( aVertex2 - 1) );
@@ -261,7 +261,7 @@ bool ANGLE_CONSTRAINT_45::Check ( int aVertex1, int aVertex2, LINE* aOriginLine,
     return true;
 }
 
-bool AREA_CONSTRAINT::Check ( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
+bool AREA_CONSTRAINT::Check( int aVertex1, int aVertex2, const LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
 {
     auto p1 = aOriginLine->CPoint( aVertex1 );
     auto p2 = aOriginLine->CPoint( aVertex2 );
@@ -288,7 +288,7 @@ class JOINT_CACHE
 };
 
 
-bool PRESERVE_VERTEX_CONSTRAINT::Check ( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
+bool PRESERVE_VERTEX_CONSTRAINT::Check( int aVertex1, int aVertex2, const LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
 {
     bool cv = false;
 
@@ -321,7 +321,7 @@ bool PRESERVE_VERTEX_CONSTRAINT::Check ( int aVertex1, int aVertex2, LINE* aOrig
 }
 
 
-bool RESTRICT_VERTEX_RANGE_CONSTRAINT::Check ( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
+bool RESTRICT_VERTEX_RANGE_CONSTRAINT::Check( int aVertex1, int aVertex2, const LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
 {
     return true;
 }
@@ -393,7 +393,7 @@ static bool pointInside2( const SHAPE_LINE_CHAIN& aL, const VECTOR2I& aP )
 }
 
 
-bool KEEP_TOPOLOGY_CONSTRAINT::Check ( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
+bool KEEP_TOPOLOGY_CONSTRAINT::Check( int aVertex1, int aVertex2, const LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
         {
     SHAPE_LINE_CHAIN encPoly = aOriginLine->CLine().Slice( aVertex1, aVertex2 );
 
@@ -410,18 +410,20 @@ bool KEEP_TOPOLOGY_CONSTRAINT::Check ( int aVertex1, int aVertex2, LINE* aOrigin
         return true;
 
     for( auto j : joints )
-        {
-        if ( j->Net() == aOriginLine->Net() )
+    {
+        if( j->Net() == aOriginLine->Net() )
             continue;
 
-        if ( pointInside2( encPoly, j->Pos() ) )
-            {
+        if( pointInside2( encPoly, j->Pos() ) )
+        {
             bool falsePositive = false;
-            for( int k = 0; k < encPoly.PointCount(); k++)
-                if(encPoly.CPoint(k) == j->Pos() )
+            for( int k = 0; k < encPoly.PointCount(); k++ )
+            {
+                if( encPoly.CPoint(k) == j->Pos() )
                 {
                     falsePositive = true;
                     break;
+                }
             }
 
             if( !falsePositive )
@@ -444,21 +446,21 @@ bool OPTIMIZER::checkColliding( ITEM* aItem, bool aUpdateCache )
 
 void OPTIMIZER::ClearConstraints()
 {
-    for (auto c : m_constraints)
+    for( auto c : m_constraints)
         delete c;
     m_constraints.clear();
 }
 
 void OPTIMIZER::AddConstraint ( OPT_CONSTRAINT *aConstraint )
-    {
+{
     m_constraints.push_back(aConstraint);
 }
 
-bool OPTIMIZER::checkConstraints(  int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
+bool OPTIMIZER::checkConstraints( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement )
 {
     for( auto c: m_constraints)
     {
-        if ( !c->Check( aVertex1, aVertex2, aOriginLine, aCurrentPath, aReplacement ) )
+        if( !c->Check( aVertex1, aVertex2, aOriginLine, aCurrentPath, aReplacement ) )
         {
             return false;
         }
@@ -610,19 +612,19 @@ bool OPTIMIZER::Optimize( LINE* aLine, LINE* aResult )
 
     bool rv = false;
 
-    if ( m_effortLevel & PRESERVE_VERTEX )
+    if( m_effortLevel & PRESERVE_VERTEX )
     {
         auto c = new PRESERVE_VERTEX_CONSTRAINT( m_world, m_preservedVertex );
         AddConstraint( c );
     }
     
-    if ( m_effortLevel & RESTRICT_VERTEX_RANGE )
+    if( m_effortLevel & RESTRICT_VERTEX_RANGE )
     {
         auto c = new RESTRICT_VERTEX_RANGE_CONSTRAINT( m_world, m_restrictedVertexRange.first, m_restrictedVertexRange.second );
         AddConstraint( c );
     }
 
-    if ( m_effortLevel & KEEP_TOPOLOGY )
+    if( m_effortLevel & KEEP_TOPOLOGY )
     {
         auto c = new KEEP_TOPOLOGY_CONSTRAINT( m_world );
         AddConstraint( c );
@@ -677,7 +679,7 @@ bool OPTIMIZER::mergeStep( LINE* aLine, SHAPE_LINE_CHAIN& aCurrentPath, int step
 
 
             bool ok = false;
-            if ( !checkColliding( aLine, bypass ) )
+            if( !checkColliding( aLine, bypass ) )
             {
                 ok = checkConstraints ( n, n + step + 1, aLine, aCurrentPath, bypass );
             }
@@ -1426,32 +1428,30 @@ bool tightenSegment( bool dir, NODE *aNode, const LINE& cur,
     return true;
 }
 
-void Tighten( NODE *aNode, SHAPE_LINE_CHAIN& aOldLine, LINE& aNewLine, LINE& aOptimized )
+void Tighten( NODE *aNode, const SHAPE_LINE_CHAIN& aOldLine, const LINE& aNewLine, LINE& aOptimized )
 {
     LINE tmp;
 
-
-
-    if ( aNewLine.SegmentCount() < 3 )
+    if( aNewLine.SegmentCount() < 3 )
         return;
 
     SHAPE_LINE_CHAIN current ( aNewLine.CLine() );
 
-    for (int step = 0; step < 3; step++)
+    for( int step = 0; step < 3; step++)
     {
         current.Simplify();
 
-        for ( int i = 0; i <= current.SegmentCount() - 3; i++)
+        for( int i = 0; i <= current.SegmentCount() - 3; i++)
         {
             SHAPE_LINE_CHAIN l_in, l_out;
 
             l_in = current.Slice(i, i+3);
-            for (int dir = 0; dir < 1; dir++)
+            for( int dir = 0; dir < 1; dir++)
             {
-                if(  tightenSegment( dir ? true : false, aNode, aNewLine, l_in, l_out ) )
+                if( tightenSegment( dir ? true : false, aNode, aNewLine, l_in, l_out ) )
                 {
                     SHAPE_LINE_CHAIN opt = current;
-                    opt.Replace(i, i+3, l_out);
+                    opt.Replace(i, i + 3, l_out);
                     auto optArea = std::abs(shovedArea( aOldLine, opt ));
                     auto prevArea = std::abs(shovedArea( aOldLine, current ));
 
diff --git a/pcbnew/router/pns_optimizer.h b/pcbnew/router/pns_optimizer.h
index aef99423ca..91a0b2ab34 100644
--- a/pcbnew/router/pns_optimizer.h
+++ b/pcbnew/router/pns_optimizer.h
@@ -64,11 +64,11 @@ public:
     static int CornerCost( const SHAPE_LINE_CHAIN& aLine );
     static int CornerCost( const LINE& aLine );
 
-    void Add( LINE& aLine );
-    void Remove( LINE& aLine );
-    void Replace( LINE& aOldLine, LINE& aNewLine );
+    void Add( const LINE& aLine );
+    void Remove( const LINE& aLine );
+    void Replace( const LINE& aOldLine, const LINE& aNewLine );
 
-    bool IsBetter( COST_ESTIMATOR& aOther, double aLengthTolerance,
+    bool IsBetter( const COST_ESTIMATOR& aOther, double aLengthTolerance,
                    double aCornerTollerace ) const;
 
     double GetLengthCost() const { return m_lengthCost; }
@@ -226,7 +226,7 @@ public:
 
     virtual ~OPT_CONSTRAINT() {};
 
-    virtual bool Check ( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) = 0;
+    virtual bool Check( int aVertex1, int aVertex2, const LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) = 0;
 
     int GetPriority() const
     {
@@ -256,7 +256,7 @@ public:
 
     virtual ~ANGLE_CONSTRAINT_45() {};
 
-    virtual bool Check ( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) override;
+    virtual bool Check( int aVertex1, int aVertex2, const LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) override;
 
 private:
     int m_entryDirectionMask;
@@ -270,7 +270,7 @@ public:
         OPT_CONSTRAINT( aWorld ),
         m_allowedArea ( aAllowedArea ) {};
 
-        virtual bool Check ( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) override;
+        virtual bool Check( int aVertex1, int aVertex2, const LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) override;
 
 private:
     BOX2I m_allowedArea;
@@ -284,7 +284,7 @@ public:
         OPT_CONSTRAINT( aWorld )
         {};
 
-    virtual bool Check ( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) override;
+    virtual bool Check( int aVertex1, int aVertex2, const LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) override;
 };
 
 class PRESERVE_VERTEX_CONSTRAINT: public OPT_CONSTRAINT
@@ -295,7 +295,7 @@ public:
         m_v( aV )
         {};
 
-    virtual bool Check ( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) override;
+    virtual bool Check( int aVertex1, int aVertex2, const LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) override;
 private:
 
     VECTOR2I m_v;
@@ -310,7 +310,7 @@ public:
         m_end( aEnd )
         {};
 
-    virtual bool Check ( int aVertex1, int aVertex2, LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) override;
+    virtual bool Check( int aVertex1, int aVertex2, const LINE* aOriginLine, const SHAPE_LINE_CHAIN& aCurrentPath, const SHAPE_LINE_CHAIN& aReplacement ) override;
 private:
 
     int m_start;
@@ -320,4 +320,4 @@ private:
 
 };
 
-#endif
+#endif // __PNS_OPTIMIZER_H
diff --git a/pcbnew/zone.h b/pcbnew/zone.h
index 171193117f..bdd6340de6 100644
--- a/pcbnew/zone.h
+++ b/pcbnew/zone.h
@@ -659,7 +659,7 @@ public:
      * Function SetFilledPolysList
      * sets the list of filled polygons.
      */
-    void SetFilledPolysList( PCB_LAYER_ID aLayer, SHAPE_POLY_SET& aPolysList )
+    void SetFilledPolysList( PCB_LAYER_ID aLayer, const SHAPE_POLY_SET& aPolysList )
     {
         m_FilledPolysList[aLayer] = aPolysList;
     }
@@ -668,7 +668,7 @@ public:
       * Function SetFilledPolysList
       * sets the list of filled polygons.
       */
-    void SetRawPolysList( PCB_LAYER_ID aLayer, SHAPE_POLY_SET& aPolysList )
+    void SetRawPolysList( PCB_LAYER_ID aLayer, const SHAPE_POLY_SET& aPolysList )
     {
         m_RawPolysList[aLayer] = aPolysList;
     }
diff --git a/utils/kicad2step/pcb/base.cpp b/utils/kicad2step/pcb/base.cpp
index 121f750ab3..0f6ae8a377 100644
--- a/utils/kicad2step/pcb/base.cpp
+++ b/utils/kicad2step/pcb/base.cpp
@@ -45,7 +45,7 @@ std::ostream& operator<<( std::ostream& aStream, const TRIPLET& aTriplet )
 }
 
 
-bool Get2DPositionAndRotation( SEXPR::SEXPR* data, DOUBLET& aPosition, double& aRotation )
+bool Get2DPositionAndRotation( const SEXPR::SEXPR* data, DOUBLET& aPosition, double& aRotation )
 {
     // form: (at X Y {rot})
     int nchild = data->GetNumberOfChildren();
@@ -130,7 +130,7 @@ bool Get2DPositionAndRotation( SEXPR::SEXPR* data, DOUBLET& aPosition, double& a
 }
 
 
-bool Get2DCoordinate( SEXPR::SEXPR* data, DOUBLET& aCoordinate )
+bool Get2DCoordinate( const SEXPR::SEXPR* data, DOUBLET& aCoordinate )
 {
     // form: (at X Y {rot})
     int nchild = data->GetNumberOfChildren();
@@ -180,7 +180,7 @@ bool Get2DCoordinate( SEXPR::SEXPR* data, DOUBLET& aCoordinate )
 }
 
 
-bool Get3DCoordinate( SEXPR::SEXPR* data, TRIPLET& aCoordinate )
+bool Get3DCoordinate( const SEXPR::SEXPR* data, TRIPLET& aCoordinate )
 {
     // form: (at X Y Z)
     int nchild = data->GetNumberOfChildren();
@@ -221,7 +221,7 @@ bool Get3DCoordinate( SEXPR::SEXPR* data, TRIPLET& aCoordinate )
 }
 
 
-bool GetXYZRotation( SEXPR::SEXPR* data, TRIPLET& aRotation )
+bool GetXYZRotation( const SEXPR::SEXPR* data, TRIPLET& aRotation )
 {
     const char bad_rotation[] = "* invalid 3D rotation";
 
diff --git a/utils/kicad2step/pcb/base.h b/utils/kicad2step/pcb/base.h
index 5a545755ba..4530f5ea89 100644
--- a/utils/kicad2step/pcb/base.h
+++ b/utils/kicad2step/pcb/base.h
@@ -93,10 +93,10 @@ struct TRIPLET
 
 std::ostream& operator<<( std::ostream& aStream, const TRIPLET& aTriplet );
 
-bool Get2DPositionAndRotation( SEXPR::SEXPR* data, DOUBLET& aPosition, double& aRotation );
-bool Get2DCoordinate( SEXPR::SEXPR* data, DOUBLET& aCoordinate );
-bool Get3DCoordinate( SEXPR::SEXPR* data, TRIPLET& aCoordinate );
-bool GetXYZRotation( SEXPR::SEXPR* data, TRIPLET& aRotation );
+bool Get2DPositionAndRotation( const SEXPR::SEXPR* data, DOUBLET& aPosition, double& aRotation );
+bool Get2DCoordinate( const SEXPR::SEXPR* data, DOUBLET& aCoordinate );
+bool Get3DCoordinate( const SEXPR::SEXPR* data, TRIPLET& aCoordinate );
+bool GetXYZRotation( const SEXPR::SEXPR* data, TRIPLET& aRotation );
 
 /**
  * Get the layer name from a layer element, if the layer is syntactically
diff --git a/utils/kicad2step/pcb/kicadpad.cpp b/utils/kicad2step/pcb/kicadpad.cpp
index 508a32056e..fa1f274096 100644
--- a/utils/kicad2step/pcb/kicadpad.cpp
+++ b/utils/kicad2step/pcb/kicadpad.cpp
@@ -49,7 +49,7 @@ KICADPAD::~KICADPAD()
 }
 
 
-bool KICADPAD::Read( SEXPR::SEXPR* aEntry )
+bool KICADPAD::Read( const SEXPR::SEXPR* aEntry )
 {
     // form: ( pad N thru_hole shape (at x y {r}) (size x y) (drill {oval} x {y}) (layers X X X) )
     int nchild = aEntry->GetNumberOfChildren();
@@ -100,7 +100,7 @@ bool KICADPAD::Read( SEXPR::SEXPR* aEntry )
 }
 
 
-bool KICADPAD::parseDrill( SEXPR::SEXPR* aDrill )
+bool KICADPAD::parseDrill( const SEXPR::SEXPR* aDrill )
 {
     // form: (drill {oval} X {Y})
     const char bad_drill[] = "* corrupt module in PCB file; bad drill";
diff --git a/utils/kicad2step/pcb/kicadpad.h b/utils/kicad2step/pcb/kicadpad.h
index db44114702..7d32e7bc50 100644
--- a/utils/kicad2step/pcb/kicadpad.h
+++ b/utils/kicad2step/pcb/kicadpad.h
@@ -45,15 +45,15 @@ class KICADPAD
 {
 private:
     bool        m_thruhole;
-    bool parseDrill( SEXPR::SEXPR* aDrill );
+    bool parseDrill( const SEXPR::SEXPR* aDrill );
 
 public:
     KICADPAD();
     virtual ~KICADPAD();
 
-    bool Read( SEXPR::SEXPR* aEntry );
+    bool Read( const SEXPR::SEXPR* aEntry );
 
-    bool IsThruHole()
+    bool IsThruHole() const
     {
         return m_thruhole;
     }
diff --git a/utils/kicad2step/pcb/oce_utils.cpp b/utils/kicad2step/pcb/oce_utils.cpp
index 8ffc6f3617..906da80494 100644
--- a/utils/kicad2step/pcb/oce_utils.cpp
+++ b/utils/kicad2step/pcb/oce_utils.cpp
@@ -308,7 +308,7 @@ bool PCBMODEL::AddOutlineSegment( KICADCURVE* aCurve )
             if( aCurve->m_startangle < 0.0 )
                 aCurve->m_startangle += 2.0 * M_PI;
 
-            double eang =  aCurve->m_startangle + aCurve->m_angle;
+            double eang = aCurve->m_startangle + aCurve->m_angle;
 
             if( eang < 0.0 )
                 eang += 2.0 * M_PI;
@@ -460,7 +460,7 @@ bool PCBMODEL::AddOutlineSegment( KICADCURVE* aCurve )
 
 
 // add a pad hole or slot
-bool PCBMODEL::AddPadHole( KICADPAD* aPad )
+bool PCBMODEL::AddPadHole( const KICADPAD* aPad )
 {
     if( NULL == aPad || !aPad->IsThruHole() )
         return false;
@@ -1623,7 +1623,7 @@ bool OUTLINE::addEdge( BRepBuilderAPI_MakeWire* aWire, KICADCURVE& aCurve, DOUBL
 }
 
 
-bool OUTLINE::testClosed( KICADCURVE& aFrontCurve, KICADCURVE& aBackCurve )
+bool OUTLINE::testClosed( const KICADCURVE& aFrontCurve, const KICADCURVE& aBackCurve )
 {
     double spx0, spy0, epx0, epy0;
     getEndPoints( aFrontCurve, spx0, spy0, epx0, epy0 );
diff --git a/utils/kicad2step/pcb/oce_utils.h b/utils/kicad2step/pcb/oce_utils.h
index a00b994266..989e735f24 100644
--- a/utils/kicad2step/pcb/oce_utils.h
+++ b/utils/kicad2step/pcb/oce_utils.h
@@ -53,7 +53,7 @@ private:
     double m_minDistance2;  // min squared distance to treat points as separate entities (mm)
 
     bool addEdge( BRepBuilderAPI_MakeWire* aWire, KICADCURVE& aCurve, DOUBLET& aLastPoint );
-    bool testClosed( KICADCURVE& aFrontCurve, KICADCURVE& aBackCurve );
+    bool testClosed( const KICADCURVE& aFrontCurve, const KICADCURVE& aBackCurve );
 
 public:
     std::list< KICADCURVE > m_curves;   // list of contiguous segments
@@ -118,7 +118,7 @@ public:
     bool AddOutlineSegment( KICADCURVE* aCurve );
 
     // add a pad hole or slot (must be in final position)
-    bool AddPadHole( KICADPAD* aPad );
+    bool AddPadHole( const KICADPAD* aPad );
 
     // add a component at the given position and orientation
     bool AddComponent( const std::string& aFileName, const std::string& aRefDes,
@@ -149,4 +149,4 @@ public:
     bool WriteSTEP( const wxString& aFileName );
 };
 
-#endif //OCE_VIS_OCE_UTILS_H
+#endif // OCE_VIS_OCE_UTILS_H