diff --git a/main/au.hh b/main/au.hh
index 745513b4..44af35b9 100644
--- a/main/au.hh
+++ b/main/au.hh
@@ -24,7 +24,7 @@
 #include <type_traits>
 #include <utility>
 
-// Version identifier: 0.3.5-3-g40c8e0c
+// Version identifier: 0.3.5-4-gf77cc5e
 // <iostream> support: INCLUDED
 // List of included units:
 //   amperes
@@ -5561,31 +5561,47 @@ struct AssociatedUnit<Constant<Unit>> : stdx::type_identity<Unit> {};
 }  // namespace au
 
 
-
 namespace au {
 
-// Define 1:1 mapping between duration types of chrono library and our library.
-template <typename RepT, typename Period>
-struct CorrespondingQuantity<std::chrono::duration<RepT, Period>> {
-    using Unit = decltype(Seconds{} * (mag<Period::num>() / mag<Period::den>()));
-    using Rep = RepT;
+// DO NOT follow this pattern to define your own units.  This is for library-defined units.
+// Instead, follow instructions at (https://aurora-opensource.github.io/au/main/howto/new-units/).
+template <typename T>
+struct MinutesLabel {
+    static constexpr const char label[] = "min";
+};
+template <typename T>
+constexpr const char MinutesLabel<T>::label[];
+struct Minutes : decltype(Seconds{} * mag<60>()), MinutesLabel<void> {
+    using MinutesLabel<void>::label;
+};
+constexpr auto minute = SingularNameFor<Minutes>{};
+constexpr auto minutes = QuantityMaker<Minutes>{};
 
-    using ChronoDuration = std::chrono::duration<Rep, Period>;
+namespace symbols {
+constexpr auto min = SymbolFor<Minutes>{};
+}
+}  // namespace au
 
-    static constexpr Rep extract_value(ChronoDuration d) { return d.count(); }
-    static constexpr ChronoDuration construct_from_value(Rep x) { return ChronoDuration{x}; }
+
+namespace au {
+
+// DO NOT follow this pattern to define your own units.  This is for library-defined units.
+// Instead, follow instructions at (https://aurora-opensource.github.io/au/main/howto/new-units/).
+template <typename T>
+struct HoursLabel {
+    static constexpr const char label[] = "h";
+};
+template <typename T>
+constexpr const char HoursLabel<T>::label[];
+struct Hours : decltype(Minutes{} * mag<60>()), HoursLabel<void> {
+    using HoursLabel<void>::label;
 };
+constexpr auto hour = SingularNameFor<Hours>{};
+constexpr auto hours = QuantityMaker<Hours>{};
 
-// Convert any Au duration quantity to an equivalent `std::chrono::duration`.
-template <typename U, typename R>
-constexpr auto as_chrono_duration(Quantity<U, R> dt) {
-    constexpr auto ratio = unit_ratio(U{}, seconds);
-    static_assert(is_rational(ratio), "Cannot convert to chrono::duration with non-rational ratio");
-    return std::chrono::duration<R,
-                                 std::ratio<get_value<std::intmax_t>(numerator(ratio)),
-                                            get_value<std::intmax_t>(denominator(ratio))>>{dt};
+namespace symbols {
+constexpr auto h = SymbolFor<Hours>{};
 }
-
 }  // namespace au
 
 
@@ -6439,3 +6455,65 @@ constexpr bool numeric_limits<au::Quantity<U, R>>::tinyness_before;
 
 }  // namespace std
 
+
+
+namespace au {
+
+// Define 1:1 mapping between duration types of chrono library and our library.
+template <typename RepT, typename Period>
+struct CorrespondingQuantity<std::chrono::duration<RepT, Period>> {
+    using Unit = decltype(Seconds{} * (mag<Period::num>() / mag<Period::den>()));
+    using Rep = RepT;
+
+    using ChronoDuration = std::chrono::duration<Rep, Period>;
+
+    static constexpr Rep extract_value(ChronoDuration d) { return d.count(); }
+    static constexpr ChronoDuration construct_from_value(Rep x) { return ChronoDuration{x}; }
+};
+
+// Define special mappings for widely used chrono types.
+template <typename ChronoType, typename AuUnit>
+struct SpecialCorrespondingQuantity {
+    using Unit = AuUnit;
+    using Rep = decltype(ChronoType{}.count());
+
+    static constexpr Rep extract_value(ChronoType d) { return d.count(); }
+    static constexpr ChronoType construct_from_value(Rep x) { return ChronoType{x}; }
+};
+
+template <>
+struct CorrespondingQuantity<std::chrono::nanoseconds>
+    : SpecialCorrespondingQuantity<std::chrono::nanoseconds, Nano<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::microseconds>
+    : SpecialCorrespondingQuantity<std::chrono::microseconds, Micro<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::milliseconds>
+    : SpecialCorrespondingQuantity<std::chrono::milliseconds, Milli<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::seconds>
+    : SpecialCorrespondingQuantity<std::chrono::seconds, Seconds> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::minutes>
+    : SpecialCorrespondingQuantity<std::chrono::minutes, Minutes> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::hours>
+    : SpecialCorrespondingQuantity<std::chrono::hours, Hours> {};
+
+// Convert any Au duration quantity to an equivalent `std::chrono::duration`.
+template <typename U, typename R>
+constexpr auto as_chrono_duration(Quantity<U, R> dt) {
+    constexpr auto ratio = unit_ratio(U{}, seconds);
+    static_assert(is_rational(ratio), "Cannot convert to chrono::duration with non-rational ratio");
+    return std::chrono::duration<R,
+                                 std::ratio<get_value<std::intmax_t>(numerator(ratio)),
+                                            get_value<std::intmax_t>(denominator(ratio))>>{dt};
+}
+
+}  // namespace au
+
diff --git a/main/au_all_units.hh b/main/au_all_units.hh
index 4415b12c..e2a02132 100644
--- a/main/au_all_units.hh
+++ b/main/au_all_units.hh
@@ -24,7 +24,7 @@
 #include <type_traits>
 #include <utility>
 
-// Version identifier: 0.3.5-3-g40c8e0c
+// Version identifier: 0.3.5-4-gf77cc5e
 // <iostream> support: INCLUDED
 // List of included units:
 //   amperes
@@ -7036,34 +7036,6 @@ constexpr bool numeric_limits<au::Quantity<U, R>>::tinyness_before;
 }  // namespace std
 
 
-
-namespace au {
-
-// Define 1:1 mapping between duration types of chrono library and our library.
-template <typename RepT, typename Period>
-struct CorrespondingQuantity<std::chrono::duration<RepT, Period>> {
-    using Unit = decltype(Seconds{} * (mag<Period::num>() / mag<Period::den>()));
-    using Rep = RepT;
-
-    using ChronoDuration = std::chrono::duration<Rep, Period>;
-
-    static constexpr Rep extract_value(ChronoDuration d) { return d.count(); }
-    static constexpr ChronoDuration construct_from_value(Rep x) { return ChronoDuration{x}; }
-};
-
-// Convert any Au duration quantity to an equivalent `std::chrono::duration`.
-template <typename U, typename R>
-constexpr auto as_chrono_duration(Quantity<U, R> dt) {
-    constexpr auto ratio = unit_ratio(U{}, seconds);
-    static_assert(is_rational(ratio), "Cannot convert to chrono::duration with non-rational ratio");
-    return std::chrono::duration<R,
-                                 std::ratio<get_value<std::intmax_t>(numerator(ratio)),
-                                            get_value<std::intmax_t>(denominator(ratio))>>{dt};
-}
-
-}  // namespace au
-
-
 namespace au {
 
 // DO NOT follow this pattern to define your own units.  This is for library-defined units.
@@ -7219,6 +7191,67 @@ constexpr auto bar = SymbolFor<Bars>{};
 
 
 
+namespace au {
+
+// Define 1:1 mapping between duration types of chrono library and our library.
+template <typename RepT, typename Period>
+struct CorrespondingQuantity<std::chrono::duration<RepT, Period>> {
+    using Unit = decltype(Seconds{} * (mag<Period::num>() / mag<Period::den>()));
+    using Rep = RepT;
+
+    using ChronoDuration = std::chrono::duration<Rep, Period>;
+
+    static constexpr Rep extract_value(ChronoDuration d) { return d.count(); }
+    static constexpr ChronoDuration construct_from_value(Rep x) { return ChronoDuration{x}; }
+};
+
+// Define special mappings for widely used chrono types.
+template <typename ChronoType, typename AuUnit>
+struct SpecialCorrespondingQuantity {
+    using Unit = AuUnit;
+    using Rep = decltype(ChronoType{}.count());
+
+    static constexpr Rep extract_value(ChronoType d) { return d.count(); }
+    static constexpr ChronoType construct_from_value(Rep x) { return ChronoType{x}; }
+};
+
+template <>
+struct CorrespondingQuantity<std::chrono::nanoseconds>
+    : SpecialCorrespondingQuantity<std::chrono::nanoseconds, Nano<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::microseconds>
+    : SpecialCorrespondingQuantity<std::chrono::microseconds, Micro<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::milliseconds>
+    : SpecialCorrespondingQuantity<std::chrono::milliseconds, Milli<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::seconds>
+    : SpecialCorrespondingQuantity<std::chrono::seconds, Seconds> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::minutes>
+    : SpecialCorrespondingQuantity<std::chrono::minutes, Minutes> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::hours>
+    : SpecialCorrespondingQuantity<std::chrono::hours, Hours> {};
+
+// Convert any Au duration quantity to an equivalent `std::chrono::duration`.
+template <typename U, typename R>
+constexpr auto as_chrono_duration(Quantity<U, R> dt) {
+    constexpr auto ratio = unit_ratio(U{}, seconds);
+    static_assert(is_rational(ratio), "Cannot convert to chrono::duration with non-rational ratio");
+    return std::chrono::duration<R,
+                                 std::ratio<get_value<std::intmax_t>(numerator(ratio)),
+                                            get_value<std::intmax_t>(denominator(ratio))>>{dt};
+}
+
+}  // namespace au
+
+
 namespace au {
 
 // DO NOT follow this pattern to define your own units.  This is for library-defined units.
@@ -7263,6 +7296,7 @@ constexpr auto W = SymbolFor<Watts>{};
 }  // namespace au
 
 
+
 namespace au {
 
 // DO NOT follow this pattern to define your own units.  This is for library-defined units.
diff --git a/main/au_all_units_noio.hh b/main/au_all_units_noio.hh
index f62c2811..2bd4c435 100644
--- a/main/au_all_units_noio.hh
+++ b/main/au_all_units_noio.hh
@@ -23,7 +23,7 @@
 #include <type_traits>
 #include <utility>
 
-// Version identifier: 0.3.5-3-g40c8e0c
+// Version identifier: 0.3.5-4-gf77cc5e
 // <iostream> support: EXCLUDED
 // List of included units:
 //   amperes
@@ -7004,34 +7004,6 @@ constexpr auto ftm = SymbolFor<Fathoms>{};
 }  // namespace au
 
 
-
-namespace au {
-
-// Define 1:1 mapping between duration types of chrono library and our library.
-template <typename RepT, typename Period>
-struct CorrespondingQuantity<std::chrono::duration<RepT, Period>> {
-    using Unit = decltype(Seconds{} * (mag<Period::num>() / mag<Period::den>()));
-    using Rep = RepT;
-
-    using ChronoDuration = std::chrono::duration<Rep, Period>;
-
-    static constexpr Rep extract_value(ChronoDuration d) { return d.count(); }
-    static constexpr ChronoDuration construct_from_value(Rep x) { return ChronoDuration{x}; }
-};
-
-// Convert any Au duration quantity to an equivalent `std::chrono::duration`.
-template <typename U, typename R>
-constexpr auto as_chrono_duration(Quantity<U, R> dt) {
-    constexpr auto ratio = unit_ratio(U{}, seconds);
-    static_assert(is_rational(ratio), "Cannot convert to chrono::duration with non-rational ratio");
-    return std::chrono::duration<R,
-                                 std::ratio<get_value<std::intmax_t>(numerator(ratio)),
-                                            get_value<std::intmax_t>(denominator(ratio))>>{dt};
-}
-
-}  // namespace au
-
-
 namespace au {
 
 // DO NOT follow this pattern to define your own units.  This is for library-defined units.
@@ -7187,6 +7159,67 @@ constexpr auto bar = SymbolFor<Bars>{};
 
 
 
+namespace au {
+
+// Define 1:1 mapping between duration types of chrono library and our library.
+template <typename RepT, typename Period>
+struct CorrespondingQuantity<std::chrono::duration<RepT, Period>> {
+    using Unit = decltype(Seconds{} * (mag<Period::num>() / mag<Period::den>()));
+    using Rep = RepT;
+
+    using ChronoDuration = std::chrono::duration<Rep, Period>;
+
+    static constexpr Rep extract_value(ChronoDuration d) { return d.count(); }
+    static constexpr ChronoDuration construct_from_value(Rep x) { return ChronoDuration{x}; }
+};
+
+// Define special mappings for widely used chrono types.
+template <typename ChronoType, typename AuUnit>
+struct SpecialCorrespondingQuantity {
+    using Unit = AuUnit;
+    using Rep = decltype(ChronoType{}.count());
+
+    static constexpr Rep extract_value(ChronoType d) { return d.count(); }
+    static constexpr ChronoType construct_from_value(Rep x) { return ChronoType{x}; }
+};
+
+template <>
+struct CorrespondingQuantity<std::chrono::nanoseconds>
+    : SpecialCorrespondingQuantity<std::chrono::nanoseconds, Nano<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::microseconds>
+    : SpecialCorrespondingQuantity<std::chrono::microseconds, Micro<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::milliseconds>
+    : SpecialCorrespondingQuantity<std::chrono::milliseconds, Milli<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::seconds>
+    : SpecialCorrespondingQuantity<std::chrono::seconds, Seconds> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::minutes>
+    : SpecialCorrespondingQuantity<std::chrono::minutes, Minutes> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::hours>
+    : SpecialCorrespondingQuantity<std::chrono::hours, Hours> {};
+
+// Convert any Au duration quantity to an equivalent `std::chrono::duration`.
+template <typename U, typename R>
+constexpr auto as_chrono_duration(Quantity<U, R> dt) {
+    constexpr auto ratio = unit_ratio(U{}, seconds);
+    static_assert(is_rational(ratio), "Cannot convert to chrono::duration with non-rational ratio");
+    return std::chrono::duration<R,
+                                 std::ratio<get_value<std::intmax_t>(numerator(ratio)),
+                                            get_value<std::intmax_t>(denominator(ratio))>>{dt};
+}
+
+}  // namespace au
+
+
 namespace au {
 
 // DO NOT follow this pattern to define your own units.  This is for library-defined units.
@@ -7231,6 +7264,7 @@ constexpr auto W = SymbolFor<Watts>{};
 }  // namespace au
 
 
+
 namespace au {
 
 // DO NOT follow this pattern to define your own units.  This is for library-defined units.
diff --git a/main/au_noio.hh b/main/au_noio.hh
index 3d8bab53..acb6af61 100644
--- a/main/au_noio.hh
+++ b/main/au_noio.hh
@@ -23,7 +23,7 @@
 #include <type_traits>
 #include <utility>
 
-// Version identifier: 0.3.5-3-g40c8e0c
+// Version identifier: 0.3.5-4-gf77cc5e
 // <iostream> support: EXCLUDED
 // List of included units:
 //   amperes
@@ -6358,31 +6358,47 @@ constexpr bool numeric_limits<au::Quantity<U, R>>::tinyness_before;
 }  // namespace std
 
 
-
 namespace au {
 
-// Define 1:1 mapping between duration types of chrono library and our library.
-template <typename RepT, typename Period>
-struct CorrespondingQuantity<std::chrono::duration<RepT, Period>> {
-    using Unit = decltype(Seconds{} * (mag<Period::num>() / mag<Period::den>()));
-    using Rep = RepT;
+// DO NOT follow this pattern to define your own units.  This is for library-defined units.
+// Instead, follow instructions at (https://aurora-opensource.github.io/au/main/howto/new-units/).
+template <typename T>
+struct MinutesLabel {
+    static constexpr const char label[] = "min";
+};
+template <typename T>
+constexpr const char MinutesLabel<T>::label[];
+struct Minutes : decltype(Seconds{} * mag<60>()), MinutesLabel<void> {
+    using MinutesLabel<void>::label;
+};
+constexpr auto minute = SingularNameFor<Minutes>{};
+constexpr auto minutes = QuantityMaker<Minutes>{};
 
-    using ChronoDuration = std::chrono::duration<Rep, Period>;
+namespace symbols {
+constexpr auto min = SymbolFor<Minutes>{};
+}
+}  // namespace au
 
-    static constexpr Rep extract_value(ChronoDuration d) { return d.count(); }
-    static constexpr ChronoDuration construct_from_value(Rep x) { return ChronoDuration{x}; }
+
+namespace au {
+
+// DO NOT follow this pattern to define your own units.  This is for library-defined units.
+// Instead, follow instructions at (https://aurora-opensource.github.io/au/main/howto/new-units/).
+template <typename T>
+struct HoursLabel {
+    static constexpr const char label[] = "h";
+};
+template <typename T>
+constexpr const char HoursLabel<T>::label[];
+struct Hours : decltype(Minutes{} * mag<60>()), HoursLabel<void> {
+    using HoursLabel<void>::label;
 };
+constexpr auto hour = SingularNameFor<Hours>{};
+constexpr auto hours = QuantityMaker<Hours>{};
 
-// Convert any Au duration quantity to an equivalent `std::chrono::duration`.
-template <typename U, typename R>
-constexpr auto as_chrono_duration(Quantity<U, R> dt) {
-    constexpr auto ratio = unit_ratio(U{}, seconds);
-    static_assert(is_rational(ratio), "Cannot convert to chrono::duration with non-rational ratio");
-    return std::chrono::duration<R,
-                                 std::ratio<get_value<std::intmax_t>(numerator(ratio)),
-                                            get_value<std::intmax_t>(denominator(ratio))>>{dt};
+namespace symbols {
+constexpr auto h = SymbolFor<Hours>{};
 }
-
 }  // namespace au
 
 
@@ -6407,3 +6423,65 @@ constexpr auto b = SymbolFor<Bits>{};
 }
 }  // namespace au
 
+
+
+namespace au {
+
+// Define 1:1 mapping between duration types of chrono library and our library.
+template <typename RepT, typename Period>
+struct CorrespondingQuantity<std::chrono::duration<RepT, Period>> {
+    using Unit = decltype(Seconds{} * (mag<Period::num>() / mag<Period::den>()));
+    using Rep = RepT;
+
+    using ChronoDuration = std::chrono::duration<Rep, Period>;
+
+    static constexpr Rep extract_value(ChronoDuration d) { return d.count(); }
+    static constexpr ChronoDuration construct_from_value(Rep x) { return ChronoDuration{x}; }
+};
+
+// Define special mappings for widely used chrono types.
+template <typename ChronoType, typename AuUnit>
+struct SpecialCorrespondingQuantity {
+    using Unit = AuUnit;
+    using Rep = decltype(ChronoType{}.count());
+
+    static constexpr Rep extract_value(ChronoType d) { return d.count(); }
+    static constexpr ChronoType construct_from_value(Rep x) { return ChronoType{x}; }
+};
+
+template <>
+struct CorrespondingQuantity<std::chrono::nanoseconds>
+    : SpecialCorrespondingQuantity<std::chrono::nanoseconds, Nano<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::microseconds>
+    : SpecialCorrespondingQuantity<std::chrono::microseconds, Micro<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::milliseconds>
+    : SpecialCorrespondingQuantity<std::chrono::milliseconds, Milli<Seconds>> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::seconds>
+    : SpecialCorrespondingQuantity<std::chrono::seconds, Seconds> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::minutes>
+    : SpecialCorrespondingQuantity<std::chrono::minutes, Minutes> {};
+
+template <>
+struct CorrespondingQuantity<std::chrono::hours>
+    : SpecialCorrespondingQuantity<std::chrono::hours, Hours> {};
+
+// Convert any Au duration quantity to an equivalent `std::chrono::duration`.
+template <typename U, typename R>
+constexpr auto as_chrono_duration(Quantity<U, R> dt) {
+    constexpr auto ratio = unit_ratio(U{}, seconds);
+    static_assert(is_rational(ratio), "Cannot convert to chrono::duration with non-rational ratio");
+    return std::chrono::duration<R,
+                                 std::ratio<get_value<std::intmax_t>(numerator(ratio)),
+                                            get_value<std::intmax_t>(denominator(ratio))>>{dt};
+}
+
+}  // namespace au
+