diff --git a/.gitattributes b/.gitattributes
index ece6ccd78f5..ad95c0a37b8 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -14,13 +14,16 @@ Algebraic_foundations/doc_tex/Algebraic_foundations_ref/AlgebraicStructureTraits
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/AlgebraicStructureTraits_Sqrt.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/AlgebraicStructureTraits_Square.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/AlgebraicStructureTraits_UnitPart.tex -text
+Algebraic_foundations/doc_tex/Algebraic_foundations_ref/Coercion_traits.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/EuclideanRing.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/Euclidean_ring_tag.tex -text
+Algebraic_foundations/doc_tex/Algebraic_foundations_ref/ExplicitInteroperable.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/Field.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/FieldWithSqrt.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/Field_tag.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/Field_with_sqrt_tag.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/FromSmallIntConstructible.tex -text
+Algebraic_foundations/doc_tex/Algebraic_foundations_ref/ImplicitInteroperable.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/IntegralDomain.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/IntegralDomainWithoutDiv.tex -text
 Algebraic_foundations/doc_tex/Algebraic_foundations_ref/Integral_domain_tag.tex -text
diff --git a/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/Coercion_traits.tex b/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/Coercion_traits.tex
new file mode 100644
index 00000000000..68dd673da1a
--- /dev/null
+++ b/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/Coercion_traits.tex
@@ -0,0 +1,33 @@
+\begin{ccRefClass}{Coercion_traits<A,B>}
+
+\ccDefinition
+
+An instance of \ccClassTemplateName\ refelcts the type coercion of the types
+{\sc A} and {\sc B}, it is symmetric in the two template arguments. 
+
+\ccInclude{CGAL/Coercion_traits.h}
+
+\ccTypes
+%=======
+
+%\ccThreeToTwo
+
+\ccNestedType{Explicit_interoperable}
+        { Tag indicating whether the two types A and B are a model of \ccc{ExplicitInteroperable} \\
+          This is either \ccc{CGAL::Tag_true} or \ccc{CGAL::Tag_false}. }
+\ccNestedType{Implicit_interoperable}
+        { Tag indicating whether the two types A and B are a model of \ccc{ImplicitInteroperable} \\
+          This is either \ccc{CGAL::Tag_true} or \ccc{CGAL::Tag_false}. }
+
+\ccNestedType{RET}
+        {The coercion type of {\sc A} and {\sc B}. \\
+        In case A and B are not \ccc{ExplicitInteroperable} this is undefined.  }
+\ccNestedType{Cast}
+        {A model of the \ccc{AdaptableFunctor} concept, providing the conversion of {\sc A} or {\sc B} to {\sc RET}. \\
+        In case A and B are not \ccc{ExplicitInteroperable} this is undefined.  }
+
+
+\ccSeeAlso
+\ccRefConceptPage{UFDomain} \\
+\ccRefConceptPage{AlgebraicStructureTraits}\\
+\end{ccRefClass} 
\ No newline at end of file
diff --git a/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/ExplicitInteroperable.tex b/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/ExplicitInteroperable.tex
new file mode 100644
index 00000000000..e8bfeb186d2
--- /dev/null
+++ b/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/ExplicitInteroperable.tex
@@ -0,0 +1,18 @@
+\begin{ccRefConcept}{ExplicitInteroperable}
+
+\ccDefinition
+
+Two types A and B are a model of the \ccc{ExplicitInteroperable} concept,
+if it is possible to derive a superior type for A and B, such that both 
+types are embeddable into this type. 
+This type is \ccc{Coercion_traits<A,B>::RET}.  
+
+In this case \ccc{Coercion_traits<A,B>::Explicit_interoperable} 
+is \ccc{Tag_true}.
+
+
+\ccSeeAlso
+\ccRefIdfierPage{Coercion_traits}\\
+\ccRefIdfierPage{ImplicitInteroperable}\\
+
+\end{ccRefConcept}
diff --git a/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/ImplicitInteroperable.tex b/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/ImplicitInteroperable.tex
new file mode 100644
index 00000000000..72a1946ed9c
--- /dev/null
+++ b/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/ImplicitInteroperable.tex
@@ -0,0 +1,23 @@
+\begin{ccRefConcept}{ImplicitInteroperable}
+
+\ccDefinition
+
+Two types A and B are a model of the \ccc{ImplicitInteroperable} concept,
+in case there is a superior type, such that binary arithmetic operations
+involing A and B result in this type. 
+This type is \ccc{Coercion_traits<A,B>::RET}. 
+
+The supported binary operations are exactly the ones provided by 
+\ccc{Coercion_traits<A,B>::RET} itself. 
+
+In this case \ccc{Coercion_traits<A,B>::Implicit_interoperable} 
+is \ccc{Tag_true}.
+
+\ccRefines
+ \ccc{ExplicitInteroperable}
+ 
+\ccSeeAlso
+\ccRefIdfierPage{Coercion_traits}\\
+\ccRefIdfierPage{ExplicitInteroperable}\\
+
+\end{ccRefConcept}
diff --git a/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/intro.tex b/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/intro.tex
index 2a04c762a44..51f2a57fd3b 100755
--- a/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/intro.tex
+++ b/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/intro.tex
@@ -121,3 +121,10 @@ Question: moved it to a global place?
 \ccRefIdfierPage{to_double}\\
 \ccRefIdfierPage{to_interval}\\
 
+
+\subsection*{Interoparbility of Types}
+\subsubsection*{Concepts}
+\ccRefConceptPage{ExplicitInteroperable}\\
+\ccRefConceptPage{InplicitInteroperable}\\
+\subsubsection*{Classes}
+\ccRefIdfierPage{Coercion_traits}\\
diff --git a/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/main.tex b/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/main.tex
index 1c64d7d5ae0..0276349e784 100755
--- a/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/main.tex
+++ b/Algebraic_foundations/doc_tex/Algebraic_foundations_ref/main.tex
@@ -74,4 +74,10 @@
 \input{Algebraic_foundations_ref/is_negative.tex}
 \input{Algebraic_foundations_ref/compare.tex}
 \input{Algebraic_foundations_ref/to_double.tex}
-\input{Algebraic_foundations_ref/to_interval.tex}
\ No newline at end of file
+\input{Algebraic_foundations_ref/to_interval.tex}
+
+%Coercion_traits
+%concepts: 
+\input{Algebraic_foundations_ref/ExplicitInteroperable.tex} 
+\input{Algebraic_foundations_ref/ImplicitInteroperable.tex} 
+\input{Algebraic_foundations_ref/Coercion_traits.tex} 
\ No newline at end of file