diff --git a/src/APIHeaderSection/APIHeaderSection_EditHeader.cxx b/src/APIHeaderSection/APIHeaderSection_EditHeader.cxx
index 92a12f5330..51adb10c11 100644
--- a/src/APIHeaderSection/APIHeaderSection_EditHeader.cxx
+++ b/src/APIHeaderSection/APIHeaderSection_EditHeader.cxx
@@ -45,29 +45,34 @@ static Standard_Boolean IsTimeStamp
     case  4 : if (uncar < '0' || uncar > '9') return Standard_False;
       break;
     case  5 : if (uncar != '-') return Standard_False;
+      Standard_FALLTHROUGH
     case  6 : if (uncar != '0' && uncar != '1') return Standard_False;
       break;
     case  7 : if (uncar < '0' || uncar > '9') return Standard_False;
       if (dizmois == '1' && (uncar < '0' || uncar > '2')) return Standard_False;
       break;
     case  8 : if (uncar != '-') return Standard_False;
+      Standard_FALLTHROUGH
     case  9 : if (uncar < '0' || uncar > '3') return Standard_False;
       break;
     case 10 : if (uncar < '0' || uncar > '9') return Standard_False;
       if (dizjour == '3' && (uncar != '0' && uncar != '1')) return Standard_False;
       break;
     case 11 : if (uncar != 'T') return Standard_False;
+      Standard_FALLTHROUGH
     case 12 : if (uncar < '0' || uncar > '2') return Standard_False;
       break;
     case 13 : if (uncar < '0' || uncar > '9') return Standard_False;
       if (dizheur == '2' && (uncar < '0' || uncar > '3')) return Standard_False;
       break;
     case 14 : if (uncar != ':') return Standard_False;
+      Standard_FALLTHROUGH
     case 15 : if (uncar < '0' || uncar > '5') return Standard_False;
       break;
     case 16 : if (uncar < '0' || uncar > '9') return Standard_False;
       break;
     case 17 : if (uncar != ':') return Standard_False;
+      Standard_FALLTHROUGH
     case 18 : if (uncar < '0' || uncar > '5') return Standard_False;
       break;
     case 19 : if (uncar < '0' || uncar > '9') return Standard_False;
diff --git a/src/Approx/Approx_CurvlinFunc.cxx b/src/Approx/Approx_CurvlinFunc.cxx
index 35e10c7d7e..37aadf579f 100644
--- a/src/Approx/Approx_CurvlinFunc.cxx
+++ b/src/Approx/Approx_CurvlinFunc.cxx
@@ -354,6 +354,7 @@ void Approx_CurvlinFunc::Trim(const Standard_Real First, const Standard_Real Las
     myC2D2 = ((Adaptor3d_CurveOnSurface *)(&(HCurOnSur->Curve())))->GetCurve();
     mySurf2 = ((Adaptor3d_CurveOnSurface *)(&(HCurOnSur->Curve())))->GetSurface();
 
+    Standard_FALLTHROUGH
   case 2:
     CurOnSur.Load(myC2D1);
     CurOnSur.Load(mySurf1);
diff --git a/src/BRepLib/BRepLib_FindSurface.cxx b/src/BRepLib/BRepLib_FindSurface.cxx
index 64451fb673..998176d365 100644
--- a/src/BRepLib/BRepLib_FindSurface.cxx
+++ b/src/BRepLib/BRepLib_FindSurface.cxx
@@ -361,12 +361,9 @@ void BRepLib_FindSurface::Init(const TopoDS_Shape&    S,
     case GeomAbs_Ellipse:
     case GeomAbs_Hyperbola:
     case GeomAbs_Parabola:
-      if (c.GetType() == GeomAbs_Line)
-        // Two points on straight segment
-        iNbPoints=2;
-      else
-        // Four points on otheranalitical curves
-        iNbPoints=4;
+      // Two points on straight segment, Four points on otheranalitical curves
+      iNbPoints = (c.GetType() == GeomAbs_Line ? 2 : 4);
+      Standard_FALLTHROUGH
     default:
       { 
         // Put some points on other curves
diff --git a/src/BRepTest/BRepTest_CheckCommands.cxx b/src/BRepTest/BRepTest_CheckCommands.cxx
index e35547afbb..d4e0ef75e5 100644
--- a/src/BRepTest/BRepTest_CheckCommands.cxx
+++ b/src/BRepTest/BRepTest_CheckCommands.cxx
@@ -1091,12 +1091,16 @@ static Standard_Integer shapeG1continuity (Draw_Interpretor& di, Standard_Intege
   nbeval = (Standard_Integer ) Draw::Atof( a[3]);
 
   switch(n)
-    { case 7  : epsG1 = Draw::Atof(a[6]);
-      case 6  : epsC0   = Draw::Atof(a[5]);
-      case 5  : epsnl    = Draw::Atof(a[4]);
-      case 4  : {} break;
-      default : return 1;
-    }
+  { 
+  case 7  : epsG1 = Draw::Atof(a[6]);
+    Standard_FALLTHROUGH
+  case 6  : epsC0 = Draw::Atof(a[5]);
+    Standard_FALLTHROUGH
+  case 5  : epsnl = Draw::Atof(a[4]);
+    Standard_FALLTHROUGH
+  case 4  : break;
+  default : return 1;
+  }
 
 
   Standard_Real pard1, parf1, U, Uf, deltaU, nb = 0;
@@ -1216,12 +1220,14 @@ static Standard_Integer shapeG0continuity (Draw_Interpretor& di, Standard_Intege
   nbeval = (Standard_Integer ) Draw::Atof( a[3]);
 
   switch(n)
-    { case 6  : epsC0   = Draw::Atof(a[5]);
-      case 5  : epsnl    = Draw::Atof(a[4]);
-      case 4  : {} break;
-      default : return 1;
-    }
-
+  { 
+  case 6  : epsC0   = Draw::Atof(a[5]);
+    Standard_FALLTHROUGH
+  case 5  : epsnl    = Draw::Atof(a[4]);
+    Standard_FALLTHROUGH
+  case 4  : break;
+  default : return 1;
+  }
 
   Standard_Real pard1, parf1, U, Uf, deltaU, nb = 0;
   Standard_Boolean isconti = Standard_True;
@@ -1337,15 +1343,20 @@ static Standard_Integer shapeG2continuity (Draw_Interpretor& di, Standard_Intege
   nbeval = (Standard_Integer ) Draw::Atof( a[3]);
 
   switch(n)
-    { 
-      case 9  :  maxlen   = Draw::Atof(a[8]);
-      case 8   : percent   = Draw::Atof(a[7]);      
-      case 7   : epsG1 = Draw::Atof(a[6]);
-      case 6  :  epsC0   = Draw::Atof(a[5]);
-      case 5  :  epsnl   = Draw::Atof(a[4]);
-      case 4  : {} break;
-      default : return 1;
-    }
+  { 
+  case 9  :  maxlen = Draw::Atof(a[8]);
+    Standard_FALLTHROUGH
+  case 8   : percent = Draw::Atof(a[7]);      
+    Standard_FALLTHROUGH
+  case 7   : epsG1 = Draw::Atof(a[6]);
+    Standard_FALLTHROUGH
+  case 6  :  epsC0 = Draw::Atof(a[5]);
+    Standard_FALLTHROUGH
+  case 5  :  epsnl = Draw::Atof(a[4]);
+    Standard_FALLTHROUGH
+  case 4  : break;
+  default : return 1;
+  }
 
 
   Standard_Real pard1, parf1, U, Uf, deltaU, nb = 0;
diff --git a/src/BndLib/BndLib.cxx b/src/BndLib/BndLib.cxx
index 2f2ef919c0..5b67936abe 100644
--- a/src/BndLib/BndLib.cxx
+++ b/src/BndLib/BndLib.cxx
@@ -137,71 +137,85 @@ namespace
         addPoint1;
         if (aFin <= 1) break;
       }
+      Standard_FALLTHROUGH
     case 2:
       {
         addPoint2;
         if (aFin <= 2) break;
       }
+      Standard_FALLTHROUGH
     case 3:
       {
         addPoint3;
         if (aFin <= 3) break;
       }
+      Standard_FALLTHROUGH
     case 4:
       {
         addPoint4;
         if (aFin <= 4) break;
       }
+      Standard_FALLTHROUGH
     case 5:
       {
         addPoint5;
         if (aFin <= 5) break;
       }
+      Standard_FALLTHROUGH
     case 6:
       {
         addPoint6;
         if (aFin <= 6) break;
       }
+      Standard_FALLTHROUGH
     case 7:
       {
         addPoint7;
         if (aFin <= 7) break;
       }
+      Standard_FALLTHROUGH
     case 8:
       {
         addPoint0;
         if (aFin <= 8) break;
       }
+      Standard_FALLTHROUGH
     case 9:
       {
         addPoint1;
         if (aFin <= 9) break;
       }  
+      Standard_FALLTHROUGH
     case 10:
       {
         addPoint2;
         if (aFin <= 10) break;
       }
+      Standard_FALLTHROUGH
     case 11:
       {
         addPoint3;
         if (aFin <= 11) break;
       }  
+      Standard_FALLTHROUGH
     case 12:
       {
         addPoint4;
         if (aFin <= 12) break;
       }  
+      Standard_FALLTHROUGH
     case 13:
       {
         addPoint5;
         if (aFin <= 13) break;
       }
+      Standard_FALLTHROUGH
     case 14:
       {
         addPoint6;
         if (aFin <= 14) break;
       }
+      Standard_FALLTHROUGH
     case 15:
       {
         addPoint7;
@@ -1271,41 +1285,49 @@ void BndLib::Add(const gp_Torus& S,const Standard_Real UMin,
       addP0;
       if (Fi2 <= 0) break;
     }
+    Standard_FALLTHROUGH
   case 1 : 
     {
       addP1;
       if (Fi2 <= 1) break;
     }
+    Standard_FALLTHROUGH
   case 2 :  
     {
       addP2;
       if (Fi2 <= 2) break;
     }
+    Standard_FALLTHROUGH
   case 3 :  
     {
       addP3;
       if (Fi2 <= 3) break;
     }
+    Standard_FALLTHROUGH
   case 4 :  
     {
       addP4;
       if (Fi2 <= 4) break;
     }
+    Standard_FALLTHROUGH
   case 5 :  
     {
       addP5;
       if (Fi2 <= 5) break;
     }
+    Standard_FALLTHROUGH
   case 6 :  
     {
       addP6;
       if (Fi2 <= 6) break;
     }
+    Standard_FALLTHROUGH
   case 7 :  
     {
       addP7;
       if (Fi2 <= 7) break;
     }
+    Standard_FALLTHROUGH
   case 8 :  
   default :
     {
@@ -1313,18 +1335,25 @@ void BndLib::Add(const gp_Torus& S,const Standard_Real UMin,
       switch (Fi2) {
       case 15 :  
         addP7;
+        Standard_FALLTHROUGH
       case 14 :  
         addP6;
+        Standard_FALLTHROUGH
       case 13 :  
         addP5;
+        Standard_FALLTHROUGH
       case 12 :  
         addP4;
+        Standard_FALLTHROUGH
       case 11 :  
         addP3;
+        Standard_FALLTHROUGH
       case 10 :  
         addP2;
+        Standard_FALLTHROUGH
       case 9 : 
         addP1;
+        Standard_FALLTHROUGH
       case 8 : 
         break;
       }    
diff --git a/src/BndLib/BndLib_AddSurface.cxx b/src/BndLib/BndLib_AddSurface.cxx
index b2f23ceeff..d55bddd3d6 100644
--- a/src/BndLib/BndLib_AddSurface.cxx
+++ b/src/BndLib/BndLib_AddSurface.cxx
@@ -460,6 +460,7 @@ void BndLib_AddSurface::Add(const Adaptor3d_Surface& S,
           break;
       }
     }
+    Standard_FALLTHROUGH
   default: 
     {
       Standard_Integer Nu = NbUSamples(S);
diff --git a/src/Extrema/Extrema_ExtCS.cxx b/src/Extrema/Extrema_ExtCS.cxx
index 1b8ae22f28..4b953656bd 100644
--- a/src/Extrema/Extrema_ExtCS.cxx
+++ b/src/Extrema/Extrema_ExtCS.cxx
@@ -129,6 +129,7 @@ void Extrema_ExtCS::Perform(const Adaptor3d_Curve& C,
       case GeomAbs_Plane:
         myExtElCS.Perform(C.Line(), myS->Plane());
         if (myExtElCS.IsParallel())   break;
+        Standard_FALLTHROUGH
 
       case GeomAbs_Torus:
       case GeomAbs_Cone:
@@ -233,6 +234,7 @@ void Extrema_ExtCS::Perform(const Adaptor3d_Curve& C,
         break;
       }
     }
+    Standard_FALLTHROUGH
   case GeomAbs_Hyperbola: 
     {
       if(myCtype == GeomAbs_Hyperbola && myStype == GeomAbs_Plane) {
@@ -241,6 +243,7 @@ void Extrema_ExtCS::Perform(const Adaptor3d_Curve& C,
         break;
       }
     }
+    Standard_FALLTHROUGH
   default:
     {
       Extrema_GenExtCS Ext;
diff --git a/src/GeomLib/GeomLib.cxx b/src/GeomLib/GeomLib.cxx
index 5d7b6a2489..da9ae9a9b4 100644
--- a/src/GeomLib/GeomLib.cxx
+++ b/src/GeomLib/GeomLib.cxx
@@ -2495,6 +2495,7 @@ void GeomLib::IsClosed (const Handle(Geom_Surface)& S,
         return;
       }
     }
+    Standard_FALLTHROUGH
     case GeomAbs_Cylinder:
     {
       if(Precision::IsInfinite(v1))
diff --git a/src/GeometryTest/GeometryTest_ContinuityCommands.cxx b/src/GeometryTest/GeometryTest_ContinuityCommands.cxx
index 449bf4d46d..abe6b42fa4 100644
--- a/src/GeometryTest/GeometryTest_ContinuityCommands.cxx
+++ b/src/GeometryTest/GeometryTest_ContinuityCommands.cxx
@@ -60,7 +60,8 @@ void InitEpsCurv(Standard_Real&  epsnl ,Standard_Real&  epsdis, Standard_Real& e
 /*********************************************************************************/
 
 static Standard_Integer surfaceCcontinuity (Draw_Interpretor& di, Standard_Integer n, const char** a)
-{ Standard_Real U1, U2, V1, V2, u1, u2, v1, v2;
+{ 
+  Standard_Real U1, U2, V1, V2, u1, u2, v1, v2;
   GeomAbs_Shape TypeCont; 
   Standard_Integer ord;
   Standard_Boolean b1, b2, b3, b4;
@@ -75,86 +76,100 @@ static Standard_Integer surfaceCcontinuity (Draw_Interpretor& di, Standard_Integ
   Handle(Geom_Surface) surf2 = DrawTrSurf::GetSurface(a[5]);
   if (surf2.IsNull()) return 1;
    
-      U1 = Draw::Atof(a[3]);
-      U2 = Draw::Atof(a[6]);
-      V1 = Draw::Atof(a[4]); 
-      V2 = Draw::Atof(a[7]); 
+  U1 = Draw::Atof(a[3]);
+  U2 = Draw::Atof(a[6]);
+  V1 = Draw::Atof(a[4]); 
+  V2 = Draw::Atof(a[7]); 
 
-      ord = Draw::Atoi(a[1]);
+  ord = Draw::Atoi(a[1]);
 
-      surf1->Bounds(u1, u2, v1, v2);
-      b1 = ((((U1>=u1)&&(U1<=u2))||((U1<=u1)&&(U1>=u2))));
-      b3 = ((((V1>=v1)&&(V1<=v2))||((V1<=v1)&&(V1>=v2))));
+  surf1->Bounds(u1, u2, v1, v2);
+  b1 = ((((U1>=u1)&&(U1<=u2))||((U1<=u1)&&(U1>=u2))));
+  b3 = ((((V1>=v1)&&(V1<=v2))||((V1<=v1)&&(V1>=v2))));
 
-      surf2->Bounds(u1, u2, v1, v2);
-      b2 = ((((U2>=u1)&&(U2<=u2))||((U2<=u1)&&(U2>=u2))));
-      b4 = ((((V2>=v1)&&(V2<=v2))||((V2<=v1)&&(V2>=v2))));
-     
-      if (!((b1 && b2)&&(b3 && b4))) return 1;
+  surf2->Bounds(u1, u2, v1, v2);
+  b2 = ((((U2>=u1)&&(U2<=u2))||((U2<=u1)&&(U2>=u2))));
+  b4 = ((((V2>=v1)&&(V2<=v2))||((V2<=v1)&&(V2>=v2))));
 
- 
-       switch ( ord )
-       { case 0 : { TypeCont=GeomAbs_C0;
-                    switch(n)
-			{ case 10  : epsC0= Draw::Atof(a[9]);
-			  case 9   : epsnl = Draw::Atof(a[8]);
-			  case 8 : {} break;
-			  default : return 1;
-			} 
-	            LocalAnalysis_SurfaceContinuity RES (surf1, U1, V1, surf2, U2, V2, 
-                    TypeCont,epsnl,epsC0,epsC1,epsC2,epsG1,perce,maxlen);
-		    //LocalAnalysis::Dump(RES,cout);
-		    Standard_SStream aSStream;
-		    LocalAnalysis::Dump(RES,aSStream);
-		    di << aSStream;
-		  } 
-		  break;
-	 case 1 : { TypeCont=GeomAbs_C1;
-                     switch(n)
-			{ case 11 : epsC1=Draw::Atof(a[10]); 
-                          case 10  : epsC0= Draw::Atof(a[9]);
-			  case 9  : epsnl = Draw::Atof(a[8]);
-			  case 8  : {} break;
-			  default : return 1;
-			} 
-	            LocalAnalysis_SurfaceContinuity RES (surf1, U1, V1, surf2, U2, V2, 
-                    TypeCont,epsnl,epsC0,epsC1,epsC2,epsG1,perce,maxlen );
-		    //LocalAnalysis::Dump(RES,cout);
-		    Standard_SStream aSStream;
-		    LocalAnalysis::Dump(RES,aSStream);
-		    di << aSStream;
-     
-		  } 
-		  break;
-	 case 2 : { TypeCont=GeomAbs_C2;
-                    switch(n)
-		       {
-                          case 12 : epsC2= Draw::Atof(a[11]); 
-                          case 11 : epsC1=Draw::Atof(a[10]); 
-                          case 10 : epsC0= Draw::Atof(a[9]);
-			  case 9  : epsnl = Draw::Atof(a[8]);
-			  case 8  : {} break;
-			  default : return 1;
-			} 
-	            LocalAnalysis_SurfaceContinuity RES (surf1, U1, V1, surf2, U2, V2, 
-                           TypeCont, epsnl,epsC0,epsC1,epsC2,epsG1,perce,maxlen  );
-                    //LocalAnalysis::Dump(RES,cout);    
-		    Standard_SStream aSStream;
-                    LocalAnalysis::Dump(RES,aSStream);    
-		    di << aSStream;
-		  }
-		  break;
+  if (!((b1 && b2)&&(b3 && b4))) return 1;
 
-	 
-        default : {} 
-       }
-   return 0; 
+  switch ( ord )
+  { 
+  case 0 : 
+    { 
+      TypeCont = GeomAbs_C0;
+      switch(n)
+      { 
+      case 10: epsC0 = Draw::Atof(a[9]);
+        Standard_FALLTHROUGH
+      case 9 : epsnl = Draw::Atof(a[8]);
+        Standard_FALLTHROUGH
+      case 8 : break;
+      default : 
+        std::cerr << "Error: invalid number of arguments: expected to get 8 - 10 parameters" << std::endl;
+        return 1;
+      } 
+    } 
+    break;
+
+  case 1 : 
+    { 
+      TypeCont = GeomAbs_C1;
+      switch(n)
+      { 
+      case 11 : epsC1 = Draw::Atof(a[10]); 
+        Standard_FALLTHROUGH
+      case 10 : epsC0 = Draw::Atof(a[9]);
+        Standard_FALLTHROUGH
+      case 9  : epsnl = Draw::Atof(a[8]);
+        Standard_FALLTHROUGH
+      case 8  : break;
+      default : 
+        std::cerr << "Error: invalid number of arguments: expected to get 8 - 11 parameters" << std::endl;
+        return 1;
+      } 
+    } 
+    break;
+
+  case 2 : 
+    { 
+      TypeCont = GeomAbs_C2;
+      switch(n)
+      {
+      case 12 : epsC2 = Draw::Atof(a[11]); 
+        Standard_FALLTHROUGH
+      case 11 : epsC1 = Draw::Atof(a[10]); 
+        Standard_FALLTHROUGH
+      case 10 : epsC0 = Draw::Atof(a[9]);
+        Standard_FALLTHROUGH
+      case 9  : epsnl = Draw::Atof(a[8]);
+        Standard_FALLTHROUGH
+      case 8  : break;
+      default : 
+        std::cerr << "Error: invalid number of arguments: expected to get 8 - 12 parameters" << std::endl;
+        return 1;
+      } 
+    }
+    break;
+  default:
+    std::cerr << "Error: invalid value of parameter 1 (" << a[1] << "): should be 0, 1, or 2" << std::endl;
+    return 1;
+  }
+
+  LocalAnalysis_SurfaceContinuity RES (surf1, U1, V1, surf2, U2, V2, 
+                                       TypeCont, epsnl, epsC0, epsC1, epsC2, epsG1, perce, maxlen);
+  //LocalAnalysis::Dump(RES,cout);    
+  Standard_SStream aSStream;
+  LocalAnalysis::Dump(RES,aSStream);    
+  di << aSStream;
+  return 0; 
 }
 
 /*********************************************************************************/
 
 static Standard_Integer surfaceGcontinuity (Draw_Interpretor& di, Standard_Integer n, const char** a)
-{ Standard_Real U1, U2, V1, V2,u1, u2, v1, v2;
+{ 
+  Standard_Real U1, U2, V1, V2,u1, u2, v1, v2;
   GeomAbs_Shape TypeCont; 
   Standard_Integer ord;
   Standard_Boolean b1, b2, b3, b4;
@@ -169,72 +184,86 @@ static Standard_Integer surfaceGcontinuity (Draw_Interpretor& di, Standard_Integ
   Handle(Geom_Surface) surf2 = DrawTrSurf::GetSurface(a[5]);
   if (surf2.IsNull()) return 1;
    
-      U1 = Draw::Atof(a[3]);
-      U2 = Draw::Atof(a[6]);
-      V1 = Draw::Atof(a[4]); 
-      V2 = Draw::Atof(a[7]); 
+  U1 = Draw::Atof(a[3]);
+  U2 = Draw::Atof(a[6]);
+  V1 = Draw::Atof(a[4]); 
+  V2 = Draw::Atof(a[7]); 
 
-      ord = Draw::Atoi(a[1]);
+  ord = Draw::Atoi(a[1]);
 
-      surf1->Bounds(u1, u2, v1, v2);
-      b1 = ((((U1>=u1)&&(U1<=u2))||((U1<=u1)&&(U1>=u2))));
-      b3 = ((((V1>=v1)&&(V1<=v2))||((V1<=v1)&&(V1>=v2))));
+  surf1->Bounds(u1, u2, v1, v2);
+  b1 = ((((U1>=u1)&&(U1<=u2))||((U1<=u1)&&(U1>=u2))));
+  b3 = ((((V1>=v1)&&(V1<=v2))||((V1<=v1)&&(V1>=v2))));
 
-      surf2->Bounds(u1, u2, v1, v2);
-      b2 = ((((U2>=u1)&&(U2<=u2))||((U2<=u1)&&(U2>=u2))));
-      b4 = ((((V2>=v1)&&(V2<=v2))||((V2<=v1)&&(V2>=v2))));
-     
-      if (!((b1 && b2)&&(b3 && b4))) return 1;
+  surf2->Bounds(u1, u2, v1, v2);
+  b2 = ((((U2>=u1)&&(U2<=u2))||((U2<=u1)&&(U2>=u2))));
+  b4 = ((((V2>=v1)&&(V2<=v2))||((V2<=v1)&&(V2>=v2))));
 
- 
-       switch ( ord )
-       { 
-	 case 1 : { TypeCont=GeomAbs_G1;
-                     switch(n)
-			 { case 11 : epsG1=Draw::Atof(a[10]); 
-                          case 10  : epsC0= Draw::Atof(a[9]);
-			  case 9  : epsnl = Draw::Atof(a[8]);
-			  case 8  : {} break;
-			  default : return 1;
-			} 
-	           LocalAnalysis_SurfaceContinuity RES (surf1, U1, V1, surf2, U2, V2, 
-                      TypeCont,epsnl,epsC0,epsC1,epsC2,epsG1,perce,maxlen );
-		    //LocalAnalysis::Dump(RES,cout);
-		    Standard_SStream aSStream;
-		    LocalAnalysis::Dump(RES,aSStream);
-		    di << aSStream;
-    
-		  } 
-		  break;
-	 case 2 : { TypeCont=GeomAbs_G2;
-                    switch(n)
-		      {   case 13 : maxlen =Draw::Atof (a[12]);
-                          case 12 :  perce=Draw::Atof(a[11]); 
-                          case 11 : epsG1=Draw::Atof(a[10]); 
-                          case 10 : epsC0= Draw::Atof(a[9]);
-			  case 9  : epsnl = Draw::Atof(a[8]);
-			  case 8  : {} break;
-			  default : return 1;
-			} 
-	           LocalAnalysis_SurfaceContinuity RES (surf1, U1, V1, surf2, U2, V2, 
-                          TypeCont, epsnl,epsC0,epsC1,epsC2,epsG1,perce,maxlen  ); 
-		    //LocalAnalysis::Dump(RES,cout);
-		    Standard_SStream aSStream;
-		    LocalAnalysis::Dump(RES,aSStream);
-		    di << aSStream;
-		  }
-		  break;
+  if (!((b1 && b2)&&(b3 && b4))) return 1;
 
-	 
-        default : {} 
-       }
-   return 0;  
+
+  switch ( ord )
+  { 
+  case 1 : 
+    { 
+      TypeCont = GeomAbs_G1;
+      switch(n)
+      { 
+      case 11 : epsG1 = Draw::Atof(a[10]); 
+        Standard_FALLTHROUGH
+      case 10 : epsC0 = Draw::Atof(a[9]);
+        Standard_FALLTHROUGH
+      case 9  : epsnl = Draw::Atof(a[8]);
+        Standard_FALLTHROUGH
+      case 8  : break;
+      default : 
+        std::cerr << "Error: invalid number of arguments: expected to get 8 - 11 parameters" << std::endl;
+        return 1;
+      } 
+    } 
+    break;
+
+  case 2 : 
+    { 
+      TypeCont = GeomAbs_G2;
+      switch(n)
+      {
+      case 13 : maxlen = Draw::Atof (a[12]);
+        Standard_FALLTHROUGH
+      case 12 : perce = Draw::Atof(a[11]); 
+        Standard_FALLTHROUGH
+      case 11 : epsG1 = Draw::Atof(a[10]); 
+        Standard_FALLTHROUGH
+      case 10 : epsC0 = Draw::Atof(a[9]);
+        Standard_FALLTHROUGH
+      case 9  : epsnl = Draw::Atof(a[8]);
+        Standard_FALLTHROUGH
+      case 8  : break;
+      default : 
+        std::cerr << "Error: invalid number of arguments: expected to get 8 - 13 parameters" << std::endl;
+        return 1;
+      } 
+    }
+    break;
+  default:
+    std::cerr << "Error: invalid value of parameter 1 (" << a[1] << "): should be 1 or 2" << std::endl;
+    return 1;
+  }
+  
+  LocalAnalysis_SurfaceContinuity RES (surf1, U1, V1, surf2, U2, V2, 
+                                       TypeCont, epsnl, epsC0, epsC1, epsC2, epsG1, perce, maxlen);
+  //LocalAnalysis::Dump(RES,cout);
+  Standard_SStream aSStream;
+  LocalAnalysis::Dump(RES,aSStream);
+  di << aSStream;
+  return 0;  
 }
 
 /*********************************************************************************/
 
 static Standard_Integer curveGcontinuity(Draw_Interpretor& di, Standard_Integer n, const char** a)
-{ Standard_Real U1, U2, u1, u2;
+{ 
+  Standard_Real U1, U2, u1, u2;
   GeomAbs_Shape  TypeCont; 
   Standard_Integer ord;
   Standard_Boolean b1, b2;
@@ -263,53 +292,69 @@ static Standard_Integer curveGcontinuity(Draw_Interpretor& di, Standard_Integer
 
   InitEpsCurv( epsnl,epsC0, epsC1, epsC2, epsG1, epsG2, percent,maxlen);
   switch ( ord )
-       { 
-	  case 1 : {
-                    switch(n)
-			{ case 9 :  epsG1=Draw::Atof(a[8]); 
-                          case 8  : epsC0= Draw::Atof(a[7]);
-			  case 7  : epsnl = Draw::Atof(a[6]);
-			  case 6  : {} break;
-			  default : return 1;
-			}                         
-                    TypeCont=GeomAbs_G1;
-	            LocalAnalysis_CurveContinuity RES (curv1, U1, curv2, U2, TypeCont, 
-                    epsnl,epsC0, epsC1, epsC2, epsG1,epsG2,percent,maxlen  );
-                    //LocalAnalysis::Dump(RES,cout); 
-		    Standard_SStream aSStream;
-                    LocalAnalysis::Dump(RES,aSStream); 
-		    di << aSStream;
-		  } 
-		  break;
-	 case 2 : { 
-                    TypeCont=GeomAbs_G2;
-                    switch(n)
-		       {case 12 :maxlen =Draw::Atof(a[11]);
-			case  11 :percent=Draw::Atof(a[10]);
-                        case 10 : epsG2= Draw::Atof(a[9]); 
-                        case 9 : epsG1=Draw::Atof(a[8]); 
-                        case 8  : epsC0= Draw::Atof(a[7]);
-			case 7  : epsnl = Draw::Atof(a[6]);
-			case 6  : {} break;
-			default : return 1;
-			} 
-	             LocalAnalysis_CurveContinuity RES (curv1, U1, curv2, U2, TypeCont,
-                         epsnl,epsC0, epsC1, epsC2, epsG1, epsG2,percent,maxlen  );
-                     //LocalAnalysis::Dump(RES,cout);   
-		    Standard_SStream aSStream;
-		    LocalAnalysis::Dump(RES,aSStream);   
-		    di << aSStream;
-		  }
-		  break; 
-        default : {}
-       }
-    return 0; 
+  { 
+  case 1 : 
+    {
+      TypeCont = GeomAbs_G1;
+      switch(n)
+      { 
+      case 9 :  epsG1 = Draw::Atof(a[8]); 
+        Standard_FALLTHROUGH
+      case 8  : epsC0 = Draw::Atof(a[7]);
+        Standard_FALLTHROUGH
+      case 7  : epsnl = Draw::Atof(a[6]);
+        Standard_FALLTHROUGH
+      case 6  : break;
+      default : 
+        std::cerr << "Error: invalid number of arguments: expected to get 6 - 8 parameters" << std::endl;
+        return 1;
+      }                         
+    } 
+    break;
+  case 2 : 
+    { 
+      TypeCont = GeomAbs_G2;
+      switch(n)
+      {
+      case 12 : maxlen = Draw::Atof(a[11]);
+        Standard_FALLTHROUGH
+      case 11 : percent = Draw::Atof(a[10]);
+        Standard_FALLTHROUGH
+      case 10 : epsG2 = Draw::Atof(a[9]); 
+        Standard_FALLTHROUGH
+      case 9  : epsG1 = Draw::Atof(a[8]); 
+        Standard_FALLTHROUGH
+      case 8  : epsC0 = Draw::Atof(a[7]);
+        Standard_FALLTHROUGH
+      case 7  : epsnl = Draw::Atof(a[6]);
+        Standard_FALLTHROUGH
+      case 6  : break;
+      default : 
+        std::cerr << "Error: invalid number of arguments: expected to get 6 - 12 parameters" << std::endl;
+        return 1;
+      } 
     }
+    break; 
+
+  default:
+    std::cerr << "Error: invalid value of parameter 1 (" << a[1] << "): should be 1 or 2" << std::endl;
+    return 1;
+  }
+
+  LocalAnalysis_CurveContinuity RES (curv1, U1, curv2, U2, TypeCont,
+                                     epsnl, epsC0, epsC1, epsC2, epsG1, epsG2, percent, maxlen);
+  //LocalAnalysis::Dump(RES,cout);   
+  Standard_SStream aSStream;
+  LocalAnalysis::Dump(RES,aSStream);   
+  di << aSStream;
+  return 0; 
+}
 
 /*********************************************************************************/
 
 static Standard_Integer curveCcontinuity(Draw_Interpretor& di, Standard_Integer n, const char** a)
-{ Standard_Real U1, U2, u1, u2;
+{ 
+  Standard_Real U1, U2, u1, u2;
   GeomAbs_Shape  TypeCont; 
   Standard_Integer ord;
   Standard_Boolean b1, b2;
@@ -321,77 +366,94 @@ static Standard_Integer curveCcontinuity(Draw_Interpretor& di, Standard_Integer
   Handle(Geom_Curve) curv2 = DrawTrSurf::GetCurve(a[4]);
   if (curv2.IsNull()) return 1;
 
-   U1 = Draw::Atof(a[3]);
-   U2 = Draw::Atof(a[5]);
- 
-   ord = Draw::Atoi(a[1]);
+  U1 = Draw::Atof(a[3]);
+  U2 = Draw::Atof(a[5]);
 
-   u1=curv1->FirstParameter();
-   u2=curv1->LastParameter();
-   b1 = ((((U1>=u1)&&(U1<=u2))||((U1<=u1)&&(U1>=u2))));
-   
-   u1=curv2->FirstParameter();
-   u2=curv2->LastParameter();   
-   b2 = ((((U2>=u1)&&(U2<=u2))||((U2<=u1)&&(U2>=u2))));
-     
-   if (!(b1 && b2)) return 1;
+  ord = Draw::Atoi(a[1]);
 
+  u1=curv1->FirstParameter();
+  u2=curv1->LastParameter();
+  b1 = ((((U1>=u1)&&(U1<=u2))||((U1<=u1)&&(U1>=u2))));
 
-   InitEpsCurv( epsnl,epsC0, epsC1, epsC2, epsG1, epsG2, percent,maxlen);
-   switch ( ord )
-       { case 0 : {  switch(n)
-			{ case 8  : epsC0= Draw::Atof(a[7]);
-			  case 7  : epsnl = Draw::Atof(a[6]);
-			  case 6  : {} break;
-			  default : return 1;
-			}                     
-                      TypeCont=GeomAbs_C0;
-	              LocalAnalysis_CurveContinuity  RES (curv1, U1, curv2, U2, TypeCont,
-                       epsnl,epsC0, epsC1, epsC2, epsG1,epsG2,percent,maxlen  );
-		     //LocalAnalysis::Dump(RES,cout);
-		     Standard_SStream aSStream;
-		     LocalAnalysis::Dump(RES,aSStream);
-		     di << aSStream;
+  u1=curv2->FirstParameter();
+  u2=curv2->LastParameter();   
+  b2 = ((((U2>=u1)&&(U2<=u2))||((U2<=u1)&&(U2>=u2))));
 
-		   }  break;
-	 case 1 : { switch(n)
-			{ case 9 : epsC1 =Draw::Atof(a[8]);
-                          case 8  : epsC0= Draw::Atof(a[7]);
-			  case 7  : epsnl = Draw::Atof(a[6]);
-			  case 6  : {} break;
-			  default : return 1;
-			}                          
-                    TypeCont=GeomAbs_C1;
-	            LocalAnalysis_CurveContinuity RES (curv1, U1, curv2, U2, TypeCont, 
-                    epsnl,epsC0, epsC1, epsC2, epsG1,epsG2,percent,maxlen  );
-                    //LocalAnalysis::Dump(RES,cout); 
-		    Standard_SStream aSStream;
-                    LocalAnalysis::Dump(RES,aSStream); 
-		    di << aSStream;
-	           
-		  } break;
-	 case 2 : {  TypeCont=GeomAbs_C2;
-                     switch(n)
-		       {
-                          case 10 : epsC2= Draw::Atof(a[9]); 
-                          case 9  : epsC1=Draw::Atof(a[8]); 
-                          case 8  : epsC0= Draw::Atof(a[7]);
-			  case 7  : epsnl = Draw::Atof(a[6]);
-			  case 6  : {} break;
-			  default : return 1;
-			} 
-	            LocalAnalysis_CurveContinuity RES (curv1, U1, curv2, U2, TypeCont, 
-                    epsnl,epsC0, epsC1, epsC2, epsG1, epsG2,percent,maxlen  );
-                    //LocalAnalysis::Dump(RES,cout);   
-		    Standard_SStream aSStream;
-                    LocalAnalysis::Dump(RES,aSStream);   
-		    di << aSStream;
-		  }
-		  break; 
-        default : {}
-       }
-    return 0;
+  if (!(b1 && b2)) return 1;
+
+  InitEpsCurv( epsnl,epsC0, epsC1, epsC2, epsG1, epsG2, percent,maxlen);
+  switch ( ord )
+  { 
+  case 0 : 
+    {
+      TypeCont = GeomAbs_C0;
+      switch(n)
+      { 
+      case 8  : epsC0 = Draw::Atof(a[7]);
+        Standard_FALLTHROUGH
+      case 7  : epsnl = Draw::Atof(a[6]);
+        Standard_FALLTHROUGH
+      case 6  : break;
+      default : 
+        std::cerr << "Error: invalid number of arguments: expected to get 6 - 8 parameters" << std::endl;
+        return 1;
+      }
+    }  
+    break;
+  case 1 : 
+    { 
+      TypeCont = GeomAbs_C1;
+      switch(n)
+      { 
+      case 9 : epsC1 = Draw::Atof(a[8]);
+        Standard_FALLTHROUGH
+      case 8 : epsC0 = Draw::Atof(a[7]);
+        Standard_FALLTHROUGH
+      case 7 : epsnl = Draw::Atof(a[6]);
+        Standard_FALLTHROUGH
+      case 6 : break;
+      default : 
+        std::cerr << "Error: invalid number of arguments: expected to get 6 - 9 parameters" << std::endl;
+        return 1;
+      }                          
+    } 
+    break;
+
+  case 2 : 
+    {  
+      TypeCont = GeomAbs_C2;
+      switch(n)
+      {
+      case 10 : epsC2 = Draw::Atof(a[9]); 
+        Standard_FALLTHROUGH
+      case 9  : epsC1 = Draw::Atof(a[8]); 
+        Standard_FALLTHROUGH
+      case 8  : epsC0 = Draw::Atof(a[7]);
+        Standard_FALLTHROUGH
+      case 7  : epsnl = Draw::Atof(a[6]);
+        Standard_FALLTHROUGH
+      case 6  : break;
+      default : 
+        std::cerr << "Error: invalid number of arguments: expected to get 6 - 10 parameters" << std::endl;
+        return 1;
+      } 
     }
+    break; 
+
+  default:
+    std::cerr << "Error: invalid value of parameter 1 (" << a[1] << "): should be 0, 1, or 2" << std::endl;
+    return 1;
+  }
+
+  LocalAnalysis_CurveContinuity RES (curv1, U1, curv2, U2, TypeCont, 
+                                     epsnl, epsC0, epsC1, epsC2, epsG1, epsG2, percent, maxlen);
+  //LocalAnalysis::Dump(RES,cout);   
+  Standard_SStream aSStream;
+  LocalAnalysis::Dump(RES,aSStream);   
+  di << aSStream;
+  return 0;
+}
+
 /***************************************************************************/
 void GeometryTest::ContinuityCommands( Draw_Interpretor& theCommands)
 {
@@ -404,8 +466,6 @@ void GeometryTest::ContinuityCommands( Draw_Interpretor& theCommands)
 
   g = "GEOMETRY curves and surfaces continuity analysis ";
 
-
-
   theCommands.Add("surfaceCcontinuity",
 		  " surfaceCcontinuity   order surf1 parU1 parV1 surf2 parU2 parV2  [eps_nul[ epsC0 [epsC1 [epsC2]]]]",  
 		  __FILE__,
diff --git a/src/IFSelect/IFSelect_SessionPilot.cxx b/src/IFSelect/IFSelect_SessionPilot.cxx
index 987c474abc..f03a41ea38 100644
--- a/src/IFSelect/IFSelect_SessionPilot.cxx
+++ b/src/IFSelect/IFSelect_SessionPilot.cxx
@@ -377,6 +377,7 @@ IFSelect_SessionPilot::IFSelect_SessionPilot (const Standard_CString prompt)
       modhelp = 1;
       cout<<"  --  Commands candidate for  xsnew  --"<<endl;
 //  HELP : soit complet (par defaut)  soit limite a xsnew
+      Standard_FALLTHROUGH
     case  0 : {                               //        ****     HELP
       Handle(TColStd_HSequenceOfAsciiString) list;
 //    Help complet : on donne la liste des commandes, sans plus (deja pas mal)
diff --git a/src/IGESConvGeom/IGESConvGeom.cxx b/src/IGESConvGeom/IGESConvGeom.cxx
index 5acd4e5ea2..09fd548996 100644
--- a/src/IGESConvGeom/IGESConvGeom.cxx
+++ b/src/IGESConvGeom/IGESConvGeom.cxx
@@ -95,8 +95,10 @@ Standard_Integer  IGESConvGeom::SplineCurveFromIGES
     switch (degree) {
     case 3 :
       coeff.SetValue(coeff.Lower()+3, gp_Pnt(DX*Di3, DY*Di3, DZ*Di3));
+        Standard_FALLTHROUGH
     case 2 :
       coeff.SetValue(coeff.Lower()+2, gp_Pnt(CX*Di2, CY*Di2, CZ*Di2));
+        Standard_FALLTHROUGH
     case 1 :
       coeff.SetValue(coeff.Lower()+1, gp_Pnt(BX*Di, BY*Di, BZ*Di));
       coeff.SetValue(coeff.Lower()+0, gp_Pnt(AX, AY, AZ));
diff --git a/src/IGESDraw/IGESDraw_GeneralModule.cxx b/src/IGESDraw/IGESDraw_GeneralModule.cxx
index 8cf2742d50..7de22dfd8c 100644
--- a/src/IGESDraw/IGESDraw_GeneralModule.cxx
+++ b/src/IGESDraw/IGESDraw_GeneralModule.cxx
@@ -178,12 +178,14 @@ IGESDraw_GeneralModule::IGESDraw_GeneralModule ()    {  }
       IGESDraw_ToolViewsVisible tool;
       tool.OwnImplied(anent,iter);
     }
+    break;
     case 14 : {
       DeclareAndCast(IGESDraw_ViewsVisibleWithAttr,anent,ent);
       if (anent.IsNull()) break;
       IGESDraw_ToolViewsVisibleWithAttr tool;
       tool.OwnImplied(anent,iter);
     }
+    break;
     default : break;
   }
 }
diff --git a/src/IGESDraw/IGESDraw_ToolDrawing.cxx b/src/IGESDraw/IGESDraw_ToolDrawing.cxx
index dfe1cff3c8..418b255d5f 100644
--- a/src/IGESDraw/IGESDraw_ToolDrawing.cxx
+++ b/src/IGESDraw/IGESDraw_ToolDrawing.cxx
@@ -277,6 +277,7 @@ void IGESDraw_ToolDrawing::OwnDump
       break; // Nothing to be dumped here
     case 5 :        // Presently level 5 and 6 have the same Dump
       S << endl;
+      Standard_FALLTHROUGH
     case 6 :
       {
 	Standard_Integer I;
diff --git a/src/IGESToBRep/IGESToBRep_TopoSurface.cxx b/src/IGESToBRep/IGESToBRep_TopoSurface.cxx
index b637c15d7d..c799e05044 100644
--- a/src/IGESToBRep/IGESToBRep_TopoSurface.cxx
+++ b/src/IGESToBRep/IGESToBRep_TopoSurface.cxx
@@ -1019,14 +1019,15 @@ TopoDS_Shape IGESToBRep_TopoSurface::TransferOffsetSurface
     }
   case TopAbs_SHELL :
     {
-      SendWarning(st, "The First Surface only will be transfered.");
       TopoDS_Iterator dabovil(igesShape);
       if (dabovil.More()) {
-	face = TopoDS::Face(dabovil.Value());
-	break;
+        SendWarning(st, "The First Surface only will be transfered.");
+        face = TopoDS::Face(dabovil.Value());
+        break;
       }
       /* else  AddF("... */
     }
+    Standard_FALLTHROUGH
   default:
     {
       Message_Msg msg1156("IGES_1156");
diff --git a/src/IntPatch/IntPatch_ALineToWLine.cxx b/src/IntPatch/IntPatch_ALineToWLine.cxx
index ed54dd94d1..3e56529b7b 100644
--- a/src/IntPatch/IntPatch_ALineToWLine.cxx
+++ b/src/IntPatch/IntPatch_ALineToWLine.cxx
@@ -101,6 +101,7 @@ static IntPatch_SpecPntType IsPoleOrSeam(const Handle(Adaptor3d_HSurface)& theS1
           break;
         }
       }
+      Standard_FALLTHROUGH
     case GeomAbs_Torus:
       if(aType == GeomAbs_Torus)
       {
@@ -113,6 +114,7 @@ static IntPatch_SpecPntType IsPoleOrSeam(const Handle(Adaptor3d_HSurface)& theS1
           break;
         }
       }
+      Standard_FALLTHROUGH
     case GeomAbs_Cylinder:
       theSingularSurfaceID = i + 1;
       AddVertexPoint(theLine, theVertex, theArrPeriods);
diff --git a/src/IntPatch/IntPatch_ImpPrmIntersection.cxx b/src/IntPatch/IntPatch_ImpPrmIntersection.cxx
index ac89bbbcbb..180ec90fc8 100644
--- a/src/IntPatch/IntPatch_ImpPrmIntersection.cxx
+++ b/src/IntPatch/IntPatch_ImpPrmIntersection.cxx
@@ -428,6 +428,7 @@ void Recadre(const Standard_Boolean ,
   case GeomAbs_Torus:
     while(V1<(V1p-1.5*M_PI)) V1+=M_PI+M_PI;
     while(V1>(V1p+1.5*M_PI)) V1-=M_PI+M_PI;
+    Standard_FALLTHROUGH
   case GeomAbs_Cylinder:
   case GeomAbs_Cone:
   case GeomAbs_Sphere:
@@ -441,6 +442,7 @@ void Recadre(const Standard_Boolean ,
   case GeomAbs_Torus:
     while(V2<(V2p-1.5*M_PI)) V2+=M_PI+M_PI;
     while(V2>(V2p+1.5*M_PI)) V2-=M_PI+M_PI;
+    Standard_FALLTHROUGH
   case GeomAbs_Cylinder:
   case GeomAbs_Cone:
   case GeomAbs_Sphere:
diff --git a/src/IntPatch/IntPatch_Intersection.cxx b/src/IntPatch/IntPatch_Intersection.cxx
index d1c3173570..bf8c949e9a 100644
--- a/src/IntPatch/IntPatch_Intersection.cxx
+++ b/src/IntPatch/IntPatch_Intersection.cxx
@@ -166,6 +166,7 @@ void IntPatch_Intersection::Perform(const Handle(Adaptor3d_HSurface)&  S1,
       if (Intersector.IsDone() && Intersector.IsEmpty())
         break;
     }
+    Standard_FALLTHROUGH
   default:
     {
       IntPatch_PrmPrmIntersection interpp;
diff --git a/src/IntTools/IntTools_EdgeEdge.cxx b/src/IntTools/IntTools_EdgeEdge.cxx
index 2f402c358b..88379192eb 100644
--- a/src/IntTools/IntTools_EdgeEdge.cxx
+++ b/src/IntTools/IntTools_EdgeEdge.cxx
@@ -1392,6 +1392,7 @@ Standard_Real ResolutionCoeff(const BRepAdaptor_Curve& theBAC,
       break;
     }
   }
+  Standard_FALLTHROUGH
   case GeomAbs_Hyperbola :
   case GeomAbs_Parabola : 
   case GeomAbs_OtherCurve :{
@@ -1467,6 +1468,7 @@ Standard_Real Resolution(const Handle(Geom_Curve)& theCurve,
       break;
     }
   }
+  Standard_FALLTHROUGH
   default:
     aRes = theResCoeff * theR3D;
     break;
diff --git a/src/Intrv/Intrv_Intervals.cxx b/src/Intrv/Intrv_Intervals.cxx
index 1446809f39..a7a961ce36 100644
--- a/src/Intrv/Intrv_Intervals.cxx
+++ b/src/Intrv/Intrv_Intervals.cxx
@@ -194,9 +194,11 @@ void Intrv_Intervals::Unite (const Intrv_Interval& Tool)
     case Intrv_Similar :
       Tins.FuseAtStart(myInter(index).Start(),
 		       myInter(index).TolStart());    // modifier le debut
+      Standard_FALLTHROUGH
     case Intrv_JustEnclosingAtEnd :
       Tins.FuseAtEnd  (myInter(index).End  (),
 		       myInter(index).TolEnd  ());    // modifier la fin
+      Standard_FALLTHROUGH
     case Intrv_Enclosing :
       myInter.Remove(index);                          // detruire et
       index--;                                        // continuer
diff --git a/src/LDOM/LDOMBasicString.cxx b/src/LDOM/LDOMBasicString.cxx
index c30b3f16a5..c64641224d 100644
--- a/src/LDOM/LDOMBasicString.cxx
+++ b/src/LDOM/LDOMBasicString.cxx
@@ -92,6 +92,7 @@ LDOMBasicString::LDOMBasicString (const LDOMBasicString& anOther)
       memcpy (myVal.ptr, anOther.myVal.ptr, aLen);
       break;
     }
+    Standard_FALLTHROUGH
   case LDOM_AsciiDoc:
   case LDOM_AsciiDocClear:
   case LDOM_AsciiHashed:
@@ -148,6 +149,7 @@ LDOMBasicString& LDOMBasicString::operator = (const LDOMBasicString& anOther)
       memcpy (myVal.ptr, anOther.myVal.ptr, aLen);
       break;
     }
+    Standard_FALLTHROUGH
   case LDOM_AsciiDoc:
   case LDOM_AsciiDocClear:
   case LDOM_AsciiHashed:
diff --git a/src/LDOM/LDOMParser.cxx b/src/LDOM/LDOMParser.cxx
index a8f0e70fd7..cf682c0eec 100644
--- a/src/LDOM/LDOMParser.cxx
+++ b/src/LDOM/LDOMParser.cxx
@@ -180,6 +180,7 @@ Standard_Boolean LDOMParser::ParseDocument (istream& theIStream, const Standard_
         break;
       }
       isDoctype = Standard_True;
+      continue;
     case LDOM_XmlReader::XML_COMMENT:
       continue;
     case LDOM_XmlReader::XML_FULL_ELEMENT:
@@ -198,6 +199,9 @@ Standard_Boolean LDOMParser::ParseDocument (istream& theIStream, const Standard_
         }
         continue;
       }
+      isError = Standard_True;
+      myError = "Expected comment or end-of-file";
+      break;
     case LDOM_XmlReader::XML_START_ELEMENT:
       if (isElement == Standard_False) {
         isElement = Standard_True;
@@ -224,11 +228,13 @@ Standard_Boolean LDOMParser::ParseDocument (istream& theIStream, const Standard_
       }
       isError = Standard_True;
       myError = "Expected comment or end-of-file";
+      break;
     case LDOM_XmlReader::XML_END_ELEMENT:
       if (endElement()) {
         isError = Standard_True;
         myError = "User abort at endElement()";
       }
+      break;
     case LDOM_XmlReader::XML_EOF:
       break;
     case LDOM_XmlReader::XML_UNKNOWN:
diff --git a/src/LDOM/LDOMString.cxx b/src/LDOM/LDOMString.cxx
index ec0aa00977..e69c452e4e 100644
--- a/src/LDOM/LDOMString.cxx
+++ b/src/LDOM/LDOMString.cxx
@@ -47,6 +47,7 @@ LDOMString::LDOMString (const LDOMBasicString&          anOther,
     break;
   case LDOM_AsciiFree:
     myType = LDOM_AsciiDoc;
+    Standard_FALLTHROUGH
   case LDOM_AsciiDocClear:
   case LDOM_AsciiDoc:
     {
diff --git a/src/LDOM/LDOM_XmlReader.cxx b/src/LDOM/LDOM_XmlReader.cxx
index 0655a9a511..401dfc79e1 100644
--- a/src/LDOM/LDOM_XmlReader.cxx
+++ b/src/LDOM/LDOM_XmlReader.cxx
@@ -215,6 +215,7 @@ LDOM_XmlReader::RecordType LDOM_XmlReader::ReadRecord (Standard_IStream& theIStr
         return XML_UNKNOWN;
       case '\0':
         if (myEOF == Standard_True) continue;
+        Standard_FALLTHROUGH
       default:
         //      Limitation: we do not treat '&' as special character
         aPtr = (const char *) memchr (myPtr, '<', myEndPtr - myPtr);
@@ -431,6 +432,7 @@ attr_name:
       switch (myPtr[0]) {
       case '=' :
         aState = STATE_ATTRIBUTE_VALUE;
+        Standard_FALLTHROUGH
       case ' ' :
       case '\t':
       case '\n':
@@ -559,6 +561,7 @@ static Standard_Boolean isName (const char  * aString,
           aNameEnd = aPtr;
           return Standard_False;
         }
+        Standard_FALLTHROUGH
       case '.' :
       case '-' :
       case '_' :
diff --git a/src/Message/Message_MsgFile.cxx b/src/Message/Message_MsgFile.cxx
index 123822d3d9..2c5deba4f4 100644
--- a/src/Message/Message_MsgFile.cxx
+++ b/src/Message/Message_MsgFile.cxx
@@ -159,6 +159,7 @@ template <class _Char> static inline Standard_Boolean loadFile (_Char * theBuffe
         aMessage += aString;
         break;
       }
+      Standard_FALLTHROUGH
     case MsgFile_WaitingMessage:
       if (isKeyword == Standard_False)
       {
@@ -168,6 +169,7 @@ template <class _Char> static inline Standard_Boolean loadFile (_Char * theBuffe
         break;
       }
       //      Pass from here to 'case MsgFile_WaitingKeyword'
+      Standard_FALLTHROUGH
     case MsgFile_WaitingKeyword:
       if (isKeyword)
       {
diff --git a/src/NCollection/NCollection_UtfIterator.lxx b/src/NCollection/NCollection_UtfIterator.lxx
index 6cee87cc5c..0813fa1152 100755
--- a/src/NCollection/NCollection_UtfIterator.lxx
+++ b/src/NCollection/NCollection_UtfIterator.lxx
@@ -79,10 +79,15 @@ inline void NCollection_UtfIterator<Type>::readUTF8()
   switch (aBytesToRead)
   {
     case 5: myCharUtf32 += *aPos++; myCharUtf32 <<= 6; // remember, illegal UTF-8
+      Standard_FALLTHROUGH
     case 4: myCharUtf32 += *aPos++; myCharUtf32 <<= 6; // remember, illegal UTF-8
+      Standard_FALLTHROUGH
     case 3: myCharUtf32 += *aPos++; myCharUtf32 <<= 6;
+      Standard_FALLTHROUGH
     case 2: myCharUtf32 += *aPos++; myCharUtf32 <<= 6;
+      Standard_FALLTHROUGH
     case 1: myCharUtf32 += *aPos++; myCharUtf32 <<= 6;
+      Standard_FALLTHROUGH
     case 0: myCharUtf32 += *aPos++;
   }
   myCharUtf32 -= offsetsFromUTF8[aBytesToRead];
diff --git a/src/OpenGl/OpenGl_AspectMarker.cxx b/src/OpenGl/OpenGl_AspectMarker.cxx
index f94d236d35..3d96ccea1e 100644
--- a/src/OpenGl/OpenGl_AspectMarker.cxx
+++ b/src/OpenGl/OpenGl_AspectMarker.cxx
@@ -1737,6 +1737,7 @@ void OpenGl_AspectMarker::Resources::BuildSprites (const Handle(OpenGl_Context)&
           Handle(TColStd_HArray1OfByte) aBitMap = fillPointBitmap (aSize);
           aMarkerImage2 = new Graphic3d_MarkerImage (aBitMap, aSize, aSize);
         }
+        Standard_FALLTHROUGH
         case Aspect_TOM_O_PLUS:
         case Aspect_TOM_O_STAR:
         case Aspect_TOM_O_X:
@@ -1754,8 +1755,10 @@ void OpenGl_AspectMarker::Resources::BuildSprites (const Handle(OpenGl_Context)&
         }
         case Aspect_TOM_RING1:
           if (aLimit == 0.0f) aLimit = aScale * 0.2f;
+          Standard_FALLTHROUGH
         case Aspect_TOM_RING2:
           if (aLimit == 0.0f) aLimit = aScale * 0.5f;
+          Standard_FALLTHROUGH
         case Aspect_TOM_RING3:
         {
           if (aLimit == 0.0f) aLimit = aScale * 0.8f;
@@ -1896,6 +1899,7 @@ void OpenGl_AspectMarker::Resources::BuildSprites (const Handle(OpenGl_Context)&
           glBitmap (aSize, aSize, (GLfloat )(0.5f * aSize), (GLfloat )(0.5f * aSize),
                     0.0f, 0.0f, &aBitMap->Array1().Value (aBitMap->Lower()));
         }
+        Standard_FALLTHROUGH
         case Aspect_TOM_O_PLUS:
         case Aspect_TOM_O_STAR:
         case Aspect_TOM_O_X:
@@ -1940,8 +1944,10 @@ void OpenGl_AspectMarker::Resources::BuildSprites (const Handle(OpenGl_Context)&
         }
         case Aspect_TOM_RING1:
           if (aLimit == 0.0f) aLimit = aScale * 0.2f;
+          Standard_FALLTHROUGH
         case Aspect_TOM_RING2:
           if (aLimit == 0.0f) aLimit = aScale * 0.5f;
+          Standard_FALLTHROUGH
         case Aspect_TOM_RING3:
         {
           if (aLimit == 0.0f) aLimit = aScale * 0.8f;
diff --git a/src/ProjLib/ProjLib_ProjectOnPlane.cxx b/src/ProjLib/ProjLib_ProjectOnPlane.cxx
index 709687f539..61375aa3ed 100644
--- a/src/ProjLib/ProjLib_ProjectOnPlane.cxx
+++ b/src/ProjLib/ProjLib_ProjectOnPlane.cxx
@@ -624,6 +624,7 @@ void ProjLib_ProjectOnPlane::Load(const Handle(Adaptor3d_HCurve)&    C,
       R1 = R2 = Circ.Radius();
 
     }
+    Standard_FALLTHROUGH
   case GeomAbs_Ellipse:
     {
       if ( Type == GeomAbs_Ellipse) {
diff --git a/src/STEPControl/STEPControl_ActorWrite.cxx b/src/STEPControl/STEPControl_ActorWrite.cxx
index 268c968ff8..e47775d05d 100644
--- a/src/STEPControl/STEPControl_ActorWrite.cxx
+++ b/src/STEPControl/STEPControl_ActorWrite.cxx
@@ -312,8 +312,8 @@ void STEPControl_ActorWrite::SetMode (const STEPControl_StepModelType M)
   case STEPControl_BrepWithVoids :     ModeTrans() = 5; break;
   case STEPControl_FacetedBrep :       ModeTrans() = 1; break;
   case STEPControl_FacetedBrepAndBrepWithVoids : ModeTrans() = 6; break;
-  case STEPControl_ShellBasedSurfaceModel :      ModeTrans() = 2;
-  case STEPControl_GeometricCurveSet :           ModeTrans() = 4;
+  case STEPControl_ShellBasedSurfaceModel :      ModeTrans() = 2; break;
+  case STEPControl_GeometricCurveSet :           ModeTrans() = 4; break;
   case STEPControl_Hybrid : ModeTrans() = 0; break;  // PAS IMPLEMENTE !!
     default: break;
   }
diff --git a/src/SelectMgr/SelectMgr_SelectionManager.cxx b/src/SelectMgr/SelectMgr_SelectionManager.cxx
index 9d8d0c876a..8ce14f4e95 100644
--- a/src/SelectMgr/SelectMgr_SelectionManager.cxx
+++ b/src/SelectMgr/SelectMgr_SelectionManager.cxx
@@ -342,6 +342,7 @@ void SelectMgr_SelectionManager::Activate (const Handle(SelectMgr_SelectableObje
       theObject->RecomputePrimitives (theMode);
       // pass through SelectMgr_TOU_Partial
     }
+    Standard_FALLTHROUGH
     case SelectMgr_TOU_Partial:
     {
       if(theObject->HasTransformation())
@@ -755,6 +756,7 @@ void SelectMgr_SelectionManager::Update (const Handle(SelectMgr_SelectableObject
           RestoreSelectionStructures (theObject, aSelection->Mode());
           // pass through SelectMgr_TOU_Partial
         }
+        Standard_FALLTHROUGH
         case SelectMgr_TOU_Partial:
         {
           theObject->UpdateTransformations (aSelection);
@@ -822,6 +824,7 @@ void SelectMgr_SelectionManager::Update (const Handle(SelectMgr_SelectableObject
           RestoreSelectionStructures (theObject, aSelection->Mode());
           // pass through SelectMgr_TOU_Partial
         }
+        Standard_FALLTHROUGH
         case SelectMgr_TOU_Partial:
         {
           theObject->UpdateTransformations (aSelection);
@@ -846,6 +849,7 @@ void SelectMgr_SelectionManager::Update (const Handle(SelectMgr_SelectableObject
           RestoreSelectionStructures (theObject, aSelection->Mode(), theSelector);
           // pass through SelectMgr_TOU_Partial
         }
+        Standard_FALLTHROUGH
         case SelectMgr_TOU_Partial:
         {
           if (theObject->HasTransformation())
diff --git a/src/Standard/Standard_Macro.hxx b/src/Standard/Standard_Macro.hxx
index fd04320593..b1038fafd6 100644
--- a/src/Standard/Standard_Macro.hxx
+++ b/src/Standard/Standard_Macro.hxx
@@ -12,13 +12,21 @@
 // Alternatively, this file may be used under the terms of Open CASCADE
 // commercial license or contractual agreement.
 
-// Purpose:   This file is intended to be the first file #included to any
-//            Open CASCADE source. It defines platform-specific pre-processor 
-//            macros necessary for correct compilation of Open CASCADE code
+//! @file
+//! This file is intended to be the first file included to any
+//! Open CASCADE source. It defines platform-specific pre-processor 
+//! macros necessary for correct compilation of Open CASCADE code.
 
 #ifndef _Standard_Macro_HeaderFile
 # define _Standard_Macro_HeaderFile
 
+//! @def Standard_OVERRIDE
+//! Should be used in declarations of virtual methods overriden in the
+//! derived classes, to cause compilation error in the case if that virtual 
+//! function disappears or changes its signature in the base class.
+//!
+//! Expands to C++11 keyword "override" on compilers that are known to
+//! suppot it; empty in other cases.
 #if defined(__cplusplus) && (__cplusplus >= 201100L)
   // part of C++11 standard
   #define Standard_OVERRIDE override
@@ -29,16 +37,42 @@
   #define Standard_OVERRIDE
 #endif
 
-// Macro for marking variables / functions as possibly unused
-// so that compiler will not emit redundant "unused" warnings.
+//! @def Standard_FALLTHROUGH
+//! Should be used in a switch statement immediately before a case label,
+//! if code associated with the previous case label may fall through to that
+//! next label (i.e. does not end with "break" or "return" etc.). 
+//! This macro indicates that the fall through is intentional and should not be 
+//! diagnosed by a compiler that warns on fallthrough.
+//!
+//! Expands to C++17 attribute statement "[[fallthrough]];" on compilers that 
+//! declare support of C++17, or to "__attribute__((fallthrough));" on 
+//! GCC 7+.
+#if defined(__cplusplus) && (__cplusplus >= 201703L)
+  // part of C++17 standard
+  #define Standard_FALLTHROUGH [[fallthrough]];
+#elif defined(__GNUC__) && (__GNUC__ >= 7)
+  // gcc 7+
+  #define Standard_FALLTHROUGH __attribute__((fallthrough));
+#else
+  #define Standard_FALLTHROUGH
+#endif
+
+//! @def Standard_UNUSED
+//! Macro for marking variables / functions as possibly unused
+//! so that compiler will not emit redundant "unused" warnings.
+//!
+//! Expands to "__attribute__((unused))" on GCC and CLang.
 #if defined(__GNUC__) || defined(__clang__)
   #define Standard_UNUSED __attribute__((unused))
 #else
   #define Standard_UNUSED
 #endif
 
-// Macro Standard_DEPRECATED("message") can be used to declare a method deprecated.
-// If OCCT_NO_DEPRECATED is defined, Standard_DEPRECATED is defined empty.
+//! @def Standard_DEPRECATED("message")
+//! Can be used in declaration of a method or a class to mark it as deprecated.
+//! Use of such method or class will cause compiler warning (if supported by 
+//! compiler and unless disabled).
+//! If macro OCCT_NO_DEPRECATED is defined, Standard_DEPRECATED is defined empty.
 #ifdef OCCT_NO_DEPRECATED
   #define Standard_DEPRECATED(theMsg)
 #else
@@ -53,9 +87,14 @@
 #endif
 #endif
 
-// Disable warnings about deprecated features.
-// This is useful for sections of code kept for backward compatibility and scheduled for removal.
-
+//! @def Standard_DISABLE_DEPRECATION_WARNINGS
+//! Disables warnings on use of deprecated features (see Standard_DEPRECATED),
+//! from the current point till appearance of Standard_ENABLE_DEPRECATION_WARNINGS macro.
+//! This is useful for sections of code kept for backward compatibility and scheduled for removal.
+//!
+//! @def Standard_ENABLE_DEPRECATION_WARNINGS
+//! Enables warnings on use of deprecated features previously disabled by
+//! Standard_DISABLE_DEPRECATION_WARNINGS.
 #if defined(__ICL) || defined (__INTEL_COMPILER)
   #define Standard_DISABLE_DEPRECATION_WARNINGS __pragma(warning(push)) __pragma(warning(disable:1478))
   #define Standard_ENABLE_DEPRECATION_WARNINGS  __pragma(warning(pop))
@@ -118,6 +157,11 @@
 
 #endif
 
+//! @def Standard_EXPORT
+//! This macro should be used in declarations of public methods 
+//! to ensure that they are exported from DLL on Windows and thus
+//! can be called from other (dependent) libraries or applications.
+
 # if defined(_WIN32) && !defined(HAVE_NO_DLL)
 
 //======================================================
@@ -181,7 +225,9 @@
 #   endif  // __Standard_DLL
 # endif  // __Standard_API
 
-// Support of Universal Windows Platform
+//! @def OCCT_UWP
+//! This macro is defined on Windows platform in the case if the code
+//! is being compiled for UWP (Universal Windows Platform).
 #if defined(WINAPI_FAMILY) && WINAPI_FAMILY == WINAPI_FAMILY_APP
  #define OCCT_UWP
 #else
diff --git a/src/TDataXtd/TDataXtd_Geometry.cxx b/src/TDataXtd/TDataXtd_Geometry.cxx
index 2f31cf4433..f2e5beefc1 100644
--- a/src/TDataXtd/TDataXtd_Geometry.cxx
+++ b/src/TDataXtd/TDataXtd_Geometry.cxx
@@ -383,52 +383,50 @@ TDataXtd_GeometryEnum  TDataXtd_Geometry::Type (const Handle(TNaming_NamedShape)
       // TopLoc_Location loc;
       Handle(Geom_Curve) curve = BRep_Tool::Curve (edge,first,last);
       if (!curve.IsNull()) {
-	if (curve->IsInstance (STANDARD_TYPE (Geom_TrimmedCurve))) {
-	  curve =  (Handle(Geom_TrimmedCurve)::DownCast (curve))->BasisCurve ();
-	}
-	if (curve->IsInstance(STANDARD_TYPE(Geom_Line))) {
-	  type = TDataXtd_LINE;
-	}
-	else if (curve->IsInstance(STANDARD_TYPE(Geom_Circle))) {
-	  type = TDataXtd_CIRCLE;
-	}
-	else if (curve->IsInstance(STANDARD_TYPE(Geom_Ellipse))) {
-	  type = TDataXtd_ELLIPSE;
-	}
-	break;
+        if (curve->IsInstance (STANDARD_TYPE (Geom_TrimmedCurve))) {
+          curve =  (Handle(Geom_TrimmedCurve)::DownCast (curve))->BasisCurve ();
+        }
+        if (curve->IsInstance(STANDARD_TYPE(Geom_Line))) {
+          type = TDataXtd_LINE;
+        }
+        else if (curve->IsInstance(STANDARD_TYPE(Geom_Circle))) {
+          type = TDataXtd_CIRCLE;
+        }
+        else if (curve->IsInstance(STANDARD_TYPE(Geom_Ellipse))) {
+          type = TDataXtd_ELLIPSE;
+        }
       }
 #ifdef OCCT_DEBUG
       else {
-	throw Standard_Failure("curve Null dans TDataXtd_Geometry");
+        throw Standard_Failure("curve Null dans TDataXtd_Geometry");
       }
 #endif
+      break;
     }
   case TopAbs_FACE : 
     {
       const TopoDS_Face& face = TopoDS::Face(shape);
       Handle(Geom_Surface) surface = BRep_Tool::Surface (face);
       if (!surface.IsNull()) {
-	if (surface->IsInstance(STANDARD_TYPE(Geom_RectangularTrimmedSurface))) { 
-	  surface = Handle(Geom_RectangularTrimmedSurface)::DownCast (surface)->BasisSurface();
-	}
-	if (surface->IsInstance(STANDARD_TYPE(Geom_CylindricalSurface))) {
-	  type = TDataXtd_CYLINDER;
-	}
-	else if (surface->IsInstance(STANDARD_TYPE(Geom_Plane))) {
-	  type = TDataXtd_PLANE;
-	}
+        if (surface->IsInstance(STANDARD_TYPE(Geom_RectangularTrimmedSurface))) { 
+          surface = Handle(Geom_RectangularTrimmedSurface)::DownCast (surface)->BasisSurface();
+        }
+        if (surface->IsInstance(STANDARD_TYPE(Geom_CylindricalSurface))) {
+          type = TDataXtd_CYLINDER;
+        }
+        else if (surface->IsInstance(STANDARD_TYPE(Geom_Plane))) {
+          type = TDataXtd_PLANE;
+        }
       } 
 #ifdef OCCT_DEBUG
       else {
-	throw Standard_Failure("surface Null dans TDataXtd_Geometry");
+        throw Standard_Failure("surface Null dans TDataXtd_Geometry");
       }
 #endif
       break;
     }
     default :
-      {
-	break;
-      }
+      break;
   }
   return type;
 }
diff --git a/src/TNaming/TNaming_Name.cxx b/src/TNaming/TNaming_Name.cxx
index 89fccc1db6..33b2ca055f 100644
--- a/src/TNaming/TNaming_Name.cxx
+++ b/src/TNaming/TNaming_Name.cxx
@@ -423,62 +423,76 @@ static TopoDS_Shape ShapeWithType(const TopoDS_Shape     theShape,
     switch (aType) {
     case TopAbs_VERTEX: // can't do something from vertex
       break;
-    case TopAbs_EDGE: {// make wire from edges
-      if (theType <= TopAbs_SOLID) break;
-      BRepBuilderAPI_MakeWire aMakeWire;
-      aMakeWire.Add(aShapes);
-      if (!aMakeWire.IsDone()) return theShape;
-      if (theType == TopAbs_WIRE) return aMakeWire.Wire();
-      aShapes.Clear(); // don't break: we can do something more of it
-      aShapes.Append(aMakeWire.Wire());
-      aListIter.Initialize(aShapes);
-    }
-    case TopAbs_WIRE: {// make faceS from wires (one per one)
-      if (theType < TopAbs_SOLID) break;
-      TopTools_ListOfShape aFaces;
-      for(;aListIter.More();aListIter.Next()) {
-	BRepBuilderAPI_MakeFace aMakeFace(TopoDS::Wire(aListIter.Value()));
-	if (!aMakeFace.IsDone()) aFaces.Append(aMakeFace.Face());
+    case TopAbs_EDGE: 
+      {
+        // make wire from edges
+        if (theType <= TopAbs_SOLID) break;
+        BRepBuilderAPI_MakeWire aMakeWire;
+        aMakeWire.Add(aShapes);
+        if (!aMakeWire.IsDone()) return theShape;
+        if (theType == TopAbs_WIRE) return aMakeWire.Wire();
+        aShapes.Clear(); // don't break: we can do something more of it
+        aShapes.Append(aMakeWire.Wire());
+        aListIter.Initialize(aShapes);
       }
-      if (theType == TopAbs_FACE) {
-	if (aFaces.Extent() == 1) return aFaces.First();
-	return theShape;
+      Standard_FALLTHROUGH
+    case TopAbs_WIRE: 
+      {
+        // make faceS from wires (one per one)
+        if (theType < TopAbs_SOLID) break;
+        TopTools_ListOfShape aFaces;
+        for(;aListIter.More();aListIter.Next()) {
+          BRepBuilderAPI_MakeFace aMakeFace(TopoDS::Wire(aListIter.Value()));
+          if (!aMakeFace.IsDone()) aFaces.Append(aMakeFace.Face());
+        }
+        if (theType == TopAbs_FACE) {
+          if (aFaces.Extent() == 1) return aFaces.First();
+          return theShape;
+        }
+        aShapes.Assign(aFaces); // don't break: we can do something more of it
+        aListIter.Initialize(aShapes);
       }
-      aShapes.Assign(aFaces); // don't break: we can do something more of it
-      aListIter.Initialize(aShapes);
-    }
-    case TopAbs_FACE: {// make shell from faces
-      if (theType < TopAbs_SOLID) break;
-      BRep_Builder aShellBuilder;
-      TopoDS_Shell aShell;
-      aShellBuilder.MakeShell(aShell);
-      for(;aListIter.More();aListIter.Next()) aShellBuilder.Add(aShell,TopoDS::Face(aListIter.Value()));
-      aShell.Closed (BRep_Tool::IsClosed (aShell));
-      if (theType == TopAbs_SHELL) return aShell;
-      aShapes.Clear(); // don't break: we can do something more of it
-      aShapes.Append(aShell);
-      aListIter.Initialize(aShapes);
-    }
-    case TopAbs_SHELL: {// make solids from shells (one per one)
-      TopTools_ListOfShape aSolids;
-      for(;aListIter.More();aListIter.Next()) {
-	BRepBuilderAPI_MakeSolid aMakeSolid(TopoDS::Shell(aListIter.Value()));
-	if (aMakeSolid.IsDone()) aSolids.Append(aMakeSolid.Solid());
+      Standard_FALLTHROUGH
+    case TopAbs_FACE: 
+      {
+        // make shell from faces
+        if (theType < TopAbs_SOLID) break;
+        BRep_Builder aShellBuilder;
+        TopoDS_Shell aShell;
+        aShellBuilder.MakeShell(aShell);
+        for(;aListIter.More();aListIter.Next()) aShellBuilder.Add(aShell,TopoDS::Face(aListIter.Value()));
+        aShell.Closed (BRep_Tool::IsClosed (aShell));
+        if (theType == TopAbs_SHELL) return aShell;
+        aShapes.Clear(); // don't break: we can do something more of it
+        aShapes.Append(aShell);
+        aListIter.Initialize(aShapes);
       }
-      if (theType == TopAbs_SOLID) {
-	if (aSolids.Extent() == 1) return aSolids.First();
-	return theShape;
+      Standard_FALLTHROUGH
+    case TopAbs_SHELL: 
+      {
+        // make solids from shells (one per one)
+        TopTools_ListOfShape aSolids;
+        for(;aListIter.More();aListIter.Next()) {
+          BRepBuilderAPI_MakeSolid aMakeSolid(TopoDS::Shell(aListIter.Value()));
+          if (aMakeSolid.IsDone()) aSolids.Append(aMakeSolid.Solid());
+        }
+        if (theType == TopAbs_SOLID) {
+          if (aSolids.Extent() == 1) return aSolids.First();
+          return theShape;
+        }
+        aShapes.Assign(aSolids); // don't break: we can do something more of it
+        aListIter.Initialize(aShapes);
+      }
+      Standard_FALLTHROUGH
+    case TopAbs_SOLID: 
+      {
+        // make compsolid from solids
+        BRep_Builder aCompBuilder;
+        TopoDS_CompSolid aCompSolid;
+        aCompBuilder.MakeCompSolid(aCompSolid);
+        for(;aListIter.More();aListIter.Next()) aCompBuilder.Add(aCompSolid,TopoDS::Solid(aListIter.Value()));
+        if (theType == TopAbs_COMPSOLID) return aCompSolid;
       }
-      aShapes.Assign(aSolids); // don't break: we can do something more of it
-      aListIter.Initialize(aShapes);
-    }
-    case TopAbs_SOLID: {// make compsolid from solids
-      BRep_Builder aCompBuilder;
-      TopoDS_CompSolid aCompSolid;
-      aCompBuilder.MakeCompSolid(aCompSolid);
-      for(;aListIter.More();aListIter.Next()) aCompBuilder.Add(aCompSolid,TopoDS::Solid(aListIter.Value()));
-      if (theType == TopAbs_COMPSOLID) return aCompSolid;
-    }
     }
   }
   return theShape;
diff --git a/src/UnitsAPI/UnitsAPI.cxx b/src/UnitsAPI/UnitsAPI.cxx
index 6adb509960..03ad492ad9 100644
--- a/src/UnitsAPI/UnitsAPI.cxx
+++ b/src/UnitsAPI/UnitsAPI.cxx
@@ -41,6 +41,7 @@ void UnitsAPI::CheckLoading (const UnitsAPI_SystemUnits aSystemUnits)
     switch (aSystemUnits) {
       case UnitsAPI_DEFAULT :
         if( !CurrentUnits.IsNull() ) break;
+        Standard_FALLTHROUGH
       case UnitsAPI_SI :  
         currentSystem = UnitsAPI_SI; 
         if( SICurrentUnits.IsNull() ) {
diff --git a/src/ViewerTest/ViewerTest_AutoUpdater.cxx b/src/ViewerTest/ViewerTest_AutoUpdater.cxx
index 62307d44f9..61f45871fa 100644
--- a/src/ViewerTest/ViewerTest_AutoUpdater.cxx
+++ b/src/ViewerTest/ViewerTest_AutoUpdater.cxx
@@ -102,6 +102,7 @@ void ViewerTest_AutoUpdater::Update()
         return;
       }
     }
+    Standard_FALLTHROUGH
     case ViewerTest_AutoUpdater::RedrawMode_Forced:
     {
       if (!myContext.IsNull())