diff --git a/include/hpcombi/epu8_impl.hpp b/include/hpcombi/epu8_impl.hpp
index a143b81..2cc6c87 100644
--- a/include/hpcombi/epu8_impl.hpp
+++ b/include/hpcombi/epu8_impl.hpp
@@ -553,6 +553,7 @@ inline std::string to_string(HPCombi::epu8 const &a) {
     return ss.str();
 }
 
+//! This type appears in the doc because we provide an equal operator for HPCombi::epu8.
 template <> struct equal_to<HPCombi::epu8> {
     bool operator()(const HPCombi::epu8 &lhs,
                     const HPCombi::epu8 &rhs) const noexcept {
@@ -560,6 +561,7 @@ template <> struct equal_to<HPCombi::epu8> {
     }
 };
 
+//! This type appears in the doc because we provide a not_equal operator for HPCombi::epu8.
 template <> struct not_equal_to<HPCombi::epu8> {
     bool operator()(const HPCombi::epu8 &lhs,
                     const HPCombi::epu8 &rhs) const noexcept {
@@ -567,6 +569,7 @@ template <> struct not_equal_to<HPCombi::epu8> {
     }
 };
 
+//! This type appears in the doc because we provide a hash function for HPCombi::epu8.
 template <> struct hash<HPCombi::epu8> {
     inline size_t operator()(HPCombi::epu8 a) const noexcept {
         unsigned __int128 v0 = simde_mm_extract_epi64(a, 0);
@@ -583,10 +586,11 @@ template <> struct hash<HPCombi::epu8> {
     }
 };
 
+//! This type appears in the doc because we provide a less operator for HPCombi::epu8.
 template <> struct less<HPCombi::epu8> {
     // WARNING: due to endianness this is not lexicographic comparison,
     //          but we don't care when using in std::set.
-    // 10% faster than calling the lexicographic comparison operator !
+    // 10% faster than calling the lexicographic comparison operator!
     inline size_t operator()(const HPCombi::epu8 &v1,
                              const HPCombi::epu8 &v2) const noexcept {
         simde__m128 v1v = simde__m128(v1), v2v = simde__m128(v2);
diff --git a/include/hpcombi/perm16.hpp b/include/hpcombi/perm16.hpp
index a412637..b0ff471 100644
--- a/include/hpcombi/perm16.hpp
+++ b/include/hpcombi/perm16.hpp
@@ -459,7 +459,9 @@ static_assert(std::is_trivial<Perm16>(), "Perm16 is not a trivial class !");
 #include "perm16_impl.hpp"
 
 namespace std {
+// Hash operators for Transf and Perm:
 
+//! This type appears in the doc because we provide a hash function for HPCombi::PTransf16.
 template <> struct hash<HPCombi::PTransf16> {
     //! A hash operator for #HPCombi::PTransf16
     size_t operator()(const HPCombi::PTransf16 &ar) const {
@@ -467,6 +469,7 @@ template <> struct hash<HPCombi::PTransf16> {
     }
 };
 
+//! This type appears in the doc because we provide a hash function for HPCombi::Transf16.
 template <> struct hash<HPCombi::Transf16> {
     //! A hash operator for #HPCombi::Transf16
     size_t operator()(const HPCombi::Transf16 &ar) const {
@@ -474,6 +477,7 @@ template <> struct hash<HPCombi::Transf16> {
     }
 };
 
+//! This type appears in the doc because we provide a hash function for HPCombi::PPerm16.
 template <> struct hash<HPCombi::PPerm16> {
     //! A hash operator for #HPCombi::PPerm16
     size_t operator()(const HPCombi::PPerm16 &ar) const {
@@ -481,6 +485,7 @@ template <> struct hash<HPCombi::PPerm16> {
     }
 };
 
+//! This type appears in the doc because we provide a hash function for HPCombi::Perm16.
 template <> struct hash<HPCombi::Perm16> {
     //! A hash operator for #HPCombi::Perm16
     size_t operator()(const HPCombi::Perm16 &ar) const { return uint64_t(ar); }
diff --git a/include/hpcombi/perm_generic_impl.hpp b/include/hpcombi/perm_generic_impl.hpp
index 5369387..72b5a45 100644
--- a/include/hpcombi/perm_generic_impl.hpp
+++ b/include/hpcombi/perm_generic_impl.hpp
@@ -119,6 +119,7 @@ bool PermGeneric<Size, Expo>::left_weak_leq(PermGeneric other) const {
 
 namespace std {
 
+//! This type appears in the doc because we provide a hash function for HPCombi::PermGeneric.
 template <size_t Size, typename Expo>
 struct hash<HPCombi::PermGeneric<Size, Expo>> {
     size_t operator()(const HPCombi::PermGeneric<Size, Expo> &ar) const {
diff --git a/include/hpcombi/vect16.hpp b/include/hpcombi/vect16.hpp
index 251167c..2019704 100644
--- a/include/hpcombi/vect16.hpp
+++ b/include/hpcombi/vect16.hpp
@@ -116,6 +116,7 @@ inline std::ostream &operator<<(std::ostream &stream,
     return operator<<(stream, ar.v);
 }
 
+//! This type appears in the doc because we provide a hash function for HPCombi::Vect16.
 template <> struct hash<HPCombi::Vect16> {
     size_t operator()(const HPCombi::Vect16 &ar) const {
         return std::hash<HPCombi::epu8>{}(ar.v);
diff --git a/include/hpcombi/vect_generic.hpp b/include/hpcombi/vect_generic.hpp
index fa89254..381b941 100644
--- a/include/hpcombi/vect_generic.hpp
+++ b/include/hpcombi/vect_generic.hpp
@@ -239,6 +239,7 @@ std::ostream &operator<<(std::ostream &stream,
     return stream;
 }
 
+//! This type appears in the doc because we provide a hash function for HPCombi::VectGeneric.
 template <size_t Size, typename Expo>
 struct hash<HPCombi::VectGeneric<Size, Expo>> {
     size_t operator()(const HPCombi::VectGeneric<Size, Expo> &ar) const {