diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Approximate_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Approximate_2.h
index 6f7dc2f49e8..bdbb25c0321 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Approximate_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Approximate_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class Approximate_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--AreMergeable_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--AreMergeable_2.h
index 4c1d9a2f332..f176e8da76f 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--AreMergeable_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--AreMergeable_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class AreMergeable_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXAtLimit_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXAtLimit_2.h
index 9bfee4bec52..052e866809d 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXAtLimit_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXAtLimit_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class CompareXAtLimit_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXNearLimit_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXNearLimit_2.h
index 6f6e42aef4f..8ace68469a0 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXNearLimit_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXNearLimit_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class CompareXNearLimit_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareX_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareX_2.h
index ceca1636428..18bfce34fc9 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareX_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareX_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class CompareX_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXy_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXy_2.h
index 2cfe6a20609..0ec0b9072bd 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXy_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareXy_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class CompareXy_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtXLeft_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtXLeft_2.h
index fc39987f5e1..7d85a4cfe7c 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtXLeft_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtXLeft_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class CompareYAtXLeft_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtXRight_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtXRight_2.h
index 6ebf32d6fb1..bd46c115c48 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtXRight_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtXRight_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class CompareYAtXRight_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtX_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtX_2.h
index 8e2ce5eccc3..8ef6be6b7e1 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtX_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYAtX_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class CompareYAtX_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYNearBoundary_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYNearBoundary_2.h
index 57d5e36ab4b..a19f6603d1c 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYNearBoundary_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--CompareYNearBoundary_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class CompareYNearBoundary_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructMaxVertex_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructMaxVertex_2.h
index 2b536f2df9f..ba333f5a07a 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructMaxVertex_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructMaxVertex_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class ConstructMaxVertex_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructMinVertex_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructMinVertex_2.h
index 34c674a581c..d6d070628fa 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructMinVertex_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructMinVertex_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class ConstructMinVertex_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructXMonotoneCurve_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructXMonotoneCurve_2.h
index dff782892b1..e6182552024 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructXMonotoneCurve_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ConstructXMonotoneCurve_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class ConstructXMonotoneCurve_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Equal_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Equal_2.h
index 79d35482596..f5c7c85db84 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Equal_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Equal_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class Equal_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Intersect_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Intersect_2.h
index 2f884fc0a2c..505b590ce54 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Intersect_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Intersect_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class Intersect_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--IsVertical_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--IsVertical_2.h
index 4f096c03040..c6410e1603c 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--IsVertical_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--IsVertical_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class IsVertical_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--MakeXMonotone_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--MakeXMonotone_2.h
index 238a61b728c..cb845435153 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--MakeXMonotone_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--MakeXMonotone_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class MakeXMonotone_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Merge_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Merge_2.h
index 9f4cbe3214f..8ba4b41ca4e 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Merge_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Merge_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class Merge_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ParameterSpaceInX_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ParameterSpaceInX_2.h
index 57755b9e7f4..0e497744b10 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ParameterSpaceInX_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ParameterSpaceInX_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class ParameterSpaceInX_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ParameterSpaceInY_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ParameterSpaceInY_2.h
index 0e193bd1819..9508237143d 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ParameterSpaceInY_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--ParameterSpaceInY_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class ParameterSpaceInY_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Split_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Split_2.h
index 95ab7f0163e..9d99297ee0a 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Split_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrTraits--Split_2.h
@@ -12,7 +12,8 @@ namespace ArrTraits {
 class Split_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--AreMergeable_2.h b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--AreMergeable_2.h
index 6a94b58de0e..4edb5917d09 100644
--- a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--AreMergeable_2.h
+++ b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--AreMergeable_2.h
@@ -12,7 +12,8 @@ namespace ArrDirectionalTraits {
 class AreMergeable_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--CompareEndpointsXy_2.h b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--CompareEndpointsXy_2.h
index 7bba6a1c1fa..61e7b66b89f 100644
--- a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--CompareEndpointsXy_2.h
+++ b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--CompareEndpointsXy_2.h
@@ -13,7 +13,8 @@ namespace ArrDirectionalTraits {
 class CompareEndpointsXy_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--ConstructOpposite_2.h b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--ConstructOpposite_2.h
index e70c4ad7c68..b6ab4d63419 100644
--- a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--ConstructOpposite_2.h
+++ b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--ConstructOpposite_2.h
@@ -13,7 +13,8 @@ namespace ArrDirectionalTraits {
 class ConstructOpposite_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Intersect_2.h b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Intersect_2.h
index 798f320d509..d9504d0a696 100644
--- a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Intersect_2.h
+++ b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Intersect_2.h
@@ -12,7 +12,8 @@ namespace ArrDirectionalTraits {
 class Intersect_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Merge_2.h b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Merge_2.h
index f334fb42ad8..d4600119803 100644
--- a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Merge_2.h
+++ b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Merge_2.h
@@ -12,7 +12,8 @@ namespace ArrDirectionalTraits {
 class Merge_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Split_2.h b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Split_2.h
index ef5ae2ac0f9..01c78cb33f2 100644
--- a/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Split_2.h
+++ b/Boolean_set_operations_2/doc/Boolean_set_operations_2/Concepts/ArrDirectionalTraits--Split_2.h
@@ -12,7 +12,8 @@ namespace ArrDirectionalTraits {
 class Split_2 {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Kernel_d/doc/Kernel_d/Concepts/Kernel--Affine_rank_d.h b/Kernel_d/doc/Kernel_d/Concepts/Kernel--Affine_rank_d.h
index 7658ab78635..698f3f177ae 100644
--- a/Kernel_d/doc/Kernel_d/Concepts/Kernel--Affine_rank_d.h
+++ b/Kernel_d/doc/Kernel_d/Concepts/Kernel--Affine_rank_d.h
@@ -10,7 +10,8 @@ A model for this must provide:
 class Kernel_d::Affine_rank_d {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*! 
diff --git a/Kernel_d/doc/Kernel_d/Concepts/Kernel--Affinely_independent_d.h b/Kernel_d/doc/Kernel_d/Concepts/Kernel--Affinely_independent_d.h
index 0f9c36a5e14..268a63dfce0 100644
--- a/Kernel_d/doc/Kernel_d/Concepts/Kernel--Affinely_independent_d.h
+++ b/Kernel_d/doc/Kernel_d/Concepts/Kernel--Affinely_independent_d.h
@@ -10,7 +10,8 @@ A model for this must provide:
 class Kernel_d::Affinely_independent_d {
 public:
 
-/// \name Has Models 
+/// \name Operations
+/// A model of this concept must provide:
 /// @{
 
 /*!