diff --git a/docs/CMakeLists.txt b/docs/CMakeLists.txt
index 5e986aa8..77960652 100644
--- a/docs/CMakeLists.txt
+++ b/docs/CMakeLists.txt
@@ -15,4 +15,3 @@ xo_docdir_sphinx_config(
     development.rst
     ubuntu-github-workflow.rst
 )
-#xo_utest_coverage_config2()
diff --git a/include/xo/unit/quantity.hpp b/include/xo/unit/quantity.hpp
index e145db16..5d549b9c 100644
--- a/include/xo/unit/quantity.hpp
+++ b/include/xo/unit/quantity.hpp
@@ -205,7 +205,7 @@ namespace xo {
                 return quantity<s_scaled_unit, r_repr_type>(this->scale_ / x);
             }
 
-            /** create quantity representing dimensionless value @x divided by this quantity
+            /** create quantity representing dimensionless value @p x divided by this quantity
              *
              *  @pre x must be an arithmetic type such as @c int or @c double
              **/
@@ -515,7 +515,7 @@ namespace xo {
         /** @addtogroup quantity-operators **/
         ///@{
 
-        /** note: won't have constexpr result w/ fractional dimension until c++26 (when ::sqrt(), ::pow() are constexpr)
+        /** note: won't have constexpr result w/ fractional dimension until c++26 (when @c sqrt(), @c pow() are constexpr)
          **/
         template <typename Q1, typename Q2>
         requires (quantity_concept<Q1>
@@ -548,7 +548,7 @@ namespace xo {
 
         /** divide quantity @p x by quantity @p y.
          *
-         *  note: won't have constexpr result w/ fractional dimension until c++26 (when ::sqrt(), ::pow() are constexpr)
+         *  note: won't have constexpr result w/ fractional dimension until c++26 (when @c sqrt(), @c pow() are constexpr)
          **/
         template <typename Q1, typename Q2>
         requires (quantity_concept<Q1>
@@ -582,7 +582,7 @@ namespace xo {
         /** add quantity @p y to quantity @p x.  Result will have the same units as @p x.
          *  Representation will be the widest of {@c x::repr_type, @c y::repr_type}.
          *
-         *  note: won't have constexpr result w/ fractional dimension until c++26 (when ::sqrt(), ::pow() are constexpr)
+         *  note: won't have constexpr result w/ fractional dimension until c++26 (when @c sqrt(), @c pow() are constexpr)
          *
          *  @pre @p x and @p y expected to have consistent dimensions
          **/
@@ -634,7 +634,7 @@ namespace xo {
         /** subtract quantity @p y from quantity @p x.  Result will have the same units as @p x.
          *  Representation will be the widest of {@c x::repr_type, @c y::repr_type}
          *
-         *  note: won't have constexpr result w/ fractional dimension until c++26 (when ::sqrt(), ::pow() are constexpr)
+         *  note: won't have constexpr result w/ fractional dimension until c++26 (when @c sqrt(), @c pow() are constexpr)
          *
          *  @pre @p x and @p y expected to have consistent dimensions
          **/
diff --git a/include/xo/unit/quantity_ops.hpp b/include/xo/unit/quantity_ops.hpp
index 28465be9..33c0c6c3 100644
--- a/include/xo/unit/quantity_ops.hpp
+++ b/include/xo/unit/quantity_ops.hpp
@@ -9,7 +9,7 @@
 
 namespace xo {
     namespace qty {
-        /** note: won't have constexpr result until c++26 (when ::sqrt(), ::pow() are constexpr)
+        /** note: won't have constexpr result until c++26 (when @c sqrt(), @c pow() are constexpr)
          **/
         template <typename Quantity, typename Quantity2>
         requires quantity_concept<Quantity> && quantity_concept<Quantity2>
@@ -19,7 +19,7 @@ namespace xo {
             return (Quantity::compare(x, y) == 0);
         }
 
-        /** note: won't have constexpr result until c++26 (when ::sqrt(), ::pow() are constexpr)
+        /** note: won't have constexpr result until c++26 (when @c sqrt(), @c pow() are constexpr)
          **/
         template <typename Quantity, typename Quantity2>
         requires quantity_concept<Quantity> && quantity_concept<Quantity2>
diff --git a/include/xo/unit/xquantity.hpp b/include/xo/unit/xquantity.hpp
index 3a2f1031..db9d8923 100644
--- a/include/xo/unit/xquantity.hpp
+++ b/include/xo/unit/xquantity.hpp
@@ -86,11 +86,11 @@ namespace xo {
 
             ///@}
 
-            /** defgroup xqautnity-constants static xquantity constants **/
+            /** @defgroup xquantity-constants static xquantity constants **/
             ///@{
 
             /** false since unit information may be unknown at compile time.
-             *  Coordinates with quantity::always_constexpr_unit
+             *  Coordinates with @c quantity::always_constexpr_unit
              **/
             static constexpr bool always_constexpr_unit = false;
 
@@ -112,10 +112,7 @@ namespace xo {
 
             ///@}
 
-            /** @defgroup xquantity-methods xquantity methods **/
-            ///@{
-
-            /** @defgroup xquantity-arithmetic-support **/
+            /** @defgroup xquantity-arithmetic-support**/
             ///@{
 
             /** create unit quantity with same unit as @c this **/
@@ -273,6 +270,9 @@ namespace xo {
                 }
             }
 
+            /** @defgroup xquantity-comparison-support xquantity comparison support methods **/
+            ///@{
+
             /** perform 3-way comparison between @c xquantity values @p x and @p y **/
             template <typename Quantity2>
             static constexpr
@@ -303,9 +303,8 @@ namespace xo {
                 *this = *this / x;
                 return *this;
             }
-            ///@}
 
-            // TODO: operator+=, operator-=
+            ///@}
 
         private:
             /** @defgroup xquantity-instance-vars **/
@@ -319,7 +318,7 @@ namespace xo {
             ///@}
         }; /*xquantity*/
 
-        /** note: won't have constexpr result until c++26 (when ::sqrt(), ::pow() are constexpr)
+        /** note: won't have constexpr result until c++26 (when @c sqrt(), @c pow() are constexpr)
          **/
         template <typename Repr = double,
                   typename Int = std::int64_t>
@@ -331,7 +330,7 @@ namespace xo {
                  u.natural_unit_);
         }
 
-        /** note: won't have constexpr result until c++26 (when ::sqrt(), ::pow() are constexpr)
+        /** note: won't have constexpr result until c++26 (when @c sqrt(), @c pow() are constexpr)
          **/
         template <typename Repr = double,
                   typename Int = std::int64_t>
@@ -340,7 +339,7 @@ namespace xo {
             return xquantity<Repr, Int>(1.0, nu);
         }
 
-        /** note: won't have constexpr result until c++26 (when ::sqrt(), ::pow() are constexpr)
+        /** note: won't have constexpr result until c++26 (when @c sqrt(), @c pow() are constexpr)
          **/
         template <typename Q1, typename Q2>
         requires (quantity_concept<Q1>