diff --git a/include/stl2/detail/concepts/callable.hpp b/include/stl2/detail/concepts/callable.hpp
index 49c5e5baa..bb766c825 100644
--- a/include/stl2/detail/concepts/callable.hpp
+++ b/include/stl2/detail/concepts/callable.hpp
@@ -94,8 +94,6 @@ STL2_OPEN_NAMESPACE {
 	template <class>
 	struct indirect_result_of {};
 
-	// Not to spec:
-	// and https://github.com/ericniebler/stl2/issues/286
 	template <class F, class... Is>
 	requires
 		Invocable<F, reference_t<Is>...>
diff --git a/include/stl2/detail/concepts/compare.hpp b/include/stl2/detail/concepts/compare.hpp
index 0b1ab95df..99c4388f4 100644
--- a/include/stl2/detail/concepts/compare.hpp
+++ b/include/stl2/detail/concepts/compare.hpp
@@ -25,7 +25,6 @@
 STL2_OPEN_NAMESPACE {
 	///////////////////////////////////////////////////////////////////////////
 	// Boolean [concepts.lib.compare.boolean]
-	// Not to spec: see https://github.com/ericniebler/stl2/issues/155
 	//
 	template <class B>
 	concept bool Boolean =
diff --git a/include/stl2/detail/concepts/core.hpp b/include/stl2/detail/concepts/core.hpp
index de53fe109..c62a5a26e 100644
--- a/include/stl2/detail/concepts/core.hpp
+++ b/include/stl2/detail/concepts/core.hpp
@@ -71,7 +71,7 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// DerivedFrom [concepts.lib.corelang.derived]
-	// Not to spec: https://github.com/ericniebler/stl2/issues/255
+	//
 	template <class T, class U>
 	concept bool DerivedFrom =
 #if defined(__GNUC__)
@@ -90,9 +90,6 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// ConvertibleTo [concepts.lib.corelang.convertibleto]
-	// Not to spec: Requires both implicit and explicit conversion with
-	//              equal results.
-	// See https://github.com/ericniebler/stl2/issues/167
 	//
 	template <class T, class U>
 	concept bool ConvertibleTo =
diff --git a/include/stl2/detail/concepts/object/assignable.hpp b/include/stl2/detail/concepts/object/assignable.hpp
index 8caed4cc0..643170674 100644
--- a/include/stl2/detail/concepts/object/assignable.hpp
+++ b/include/stl2/detail/concepts/object/assignable.hpp
@@ -22,8 +22,6 @@ STL2_OPEN_NAMESPACE {
 	///////////////////////////////////////////////////////////////////////////
 	// Assignable [concepts.lib.corelang.assignable]
 	//
-	// Not to spec
-	// See https://github.com/ericniebler/stl2/issues/229
 	template <class T, class U>
 	concept bool Assignable =
 		_Is<T, is_lvalue_reference> &&
diff --git a/include/stl2/detail/concepts/object/movable.hpp b/include/stl2/detail/concepts/object/movable.hpp
index 6e4777a4c..ab1a35757 100644
--- a/include/stl2/detail/concepts/object/movable.hpp
+++ b/include/stl2/detail/concepts/object/movable.hpp
@@ -22,8 +22,6 @@ STL2_OPEN_NAMESPACE {
 	///////////////////////////////////////////////////////////////////////////
 	// Movable [concepts.lib.object.movable]
 	//
-	// Not to spec
-	// https://github.com/ericniebler/stl2/issues/310
 	template <class T>
 	concept bool Movable =
 		ext::Object<T> &&
diff --git a/include/stl2/detail/concepts/object/move_constructible.hpp b/include/stl2/detail/concepts/object/move_constructible.hpp
index a1ab2b598..c18aa68d4 100644
--- a/include/stl2/detail/concepts/object/move_constructible.hpp
+++ b/include/stl2/detail/concepts/object/move_constructible.hpp
@@ -61,8 +61,7 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// Destructible [concepts.lib.object.destructible]
-	// Not to spec
-	// https://github.com/ericniebler/stl2/issues/301
+	//
 	template <class T>
 	concept bool Destructible =
 		_Is<T, is_nothrow_destructible> && __addressable<T>;
@@ -76,8 +75,7 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// Constructible [concepts.lib.object.constructible]
-	// Not to spec
-	// See https://github.com/ericniebler/stl2/issues/301
+	//
 	template <class T, class... Args>
 	concept bool Constructible =
 		Destructible<T> && _Is<T, is_constructible, Args...>;
@@ -91,8 +89,7 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// DefaultConstructible [concepts.lib.object.defaultconstructible]
-	// Not to spec
-	// https://github.com/ericniebler/stl2/issues/301
+	//
 	template <class T>
 	concept bool DefaultConstructible =
 		Constructible<T>;
@@ -106,8 +103,7 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// MoveConstructible [concepts.lib.object.moveconstructible]
-	// Not to spec
-	// https://github.com/ericniebler/stl2/issues/313
+	//
 	template <class T>
 	concept bool MoveConstructible =
 		Constructible<T, T> && ConvertibleTo<T, T>;
diff --git a/include/stl2/detail/concepts/object/semiregular.hpp b/include/stl2/detail/concepts/object/semiregular.hpp
index 0625e240b..7aab066e9 100644
--- a/include/stl2/detail/concepts/object/semiregular.hpp
+++ b/include/stl2/detail/concepts/object/semiregular.hpp
@@ -23,9 +23,7 @@
 STL2_OPEN_NAMESPACE {
 	///////////////////////////////////////////////////////////////////////////
 	// CopyConstructible [concepts.lib.object.copyconstructible]
-	// Not to spec
-	// https://github.com/ericniebler/stl2/issues/301
-	// https://github.com/ericniebler/stl2/issues/313
+	//
 	template <class T>
 	concept bool CopyConstructible =
 		MoveConstructible<T> &&
diff --git a/include/stl2/detail/iterator/common_iterator.hpp b/include/stl2/detail/iterator/common_iterator.hpp
index 2883f8425..1cc2cb321 100644
--- a/include/stl2/detail/iterator/common_iterator.hpp
+++ b/include/stl2/detail/iterator/common_iterator.hpp
@@ -172,20 +172,16 @@ STL2_OPEN_NAMESPACE {
 	public:
 		using difference_type = difference_type_t<I>;
 
-		// Not to spec: constexpr per P0579
 		constexpr common_iterator() = default;
 
-		// Not to spec: constexpr per P0579
 		constexpr common_iterator(I i)
 		noexcept(is_nothrow_constructible<variant<I, S>, I>::value)
 		: v_{std::move(i)} {}
 
-		// Not to spec: constexpr per P0579
 		constexpr common_iterator(S s)
 		noexcept(is_nothrow_constructible<variant<I, S>, S>::value)
 		: v_{std::move(s)} {}
 
-		// Not to spec: constexpr per P0579
 		template <ConvertibleTo<I> II, ConvertibleTo<S> SS>
 		constexpr common_iterator(const common_iterator<II, SS>& i)
 		noexcept(
@@ -229,8 +225,7 @@ STL2_OPEN_NAMESPACE {
 			++__stl2::get_unchecked<I>(v_);
 			return *this;
 		}
-		// Not to spec:
-		// https://github.com/ericniebler/stl2/issues/232
+
 		decltype(auto) operator++(int)
 		noexcept(noexcept((decltype(declval<I&>()++))declval<I&>()++)) {
 			STL2_EXPECT(__stl2::holds_alternative<I>(v_));
@@ -245,8 +240,6 @@ STL2_OPEN_NAMESPACE {
 			return tmp;
 		}
 
-		// Not to spec:
-		// https://github.com/ericniebler/stl2/issues/245
 		friend rvalue_reference_t<I> iter_move(
 			const common_iterator& i)
 			noexcept(noexcept(__stl2::iter_move(std::declval<const I&>())))
diff --git a/include/stl2/detail/iterator/concepts.hpp b/include/stl2/detail/iterator/concepts.hpp
index 7285fa0d4..6312c443b 100644
--- a/include/stl2/detail/iterator/concepts.hpp
+++ b/include/stl2/detail/iterator/concepts.hpp
@@ -53,9 +53,6 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// iter_move
-	// Not to spec: Uses a two-step dispatch instead of requiring user overloads
-	// to compete with the default overloads in overload resolution.
-	// See https://github.com/ericniebler/stl2/issues/242
 	//
 	namespace __iter_move {
 		// Not a poison pill, simply a non-ADL block.
@@ -108,8 +105,7 @@ STL2_OPEN_NAMESPACE {
 	///////////////////////////////////////////////////////////////////////////
 	// value_type [readable.iterators]
 	// Not to spec:
-	// * Implements #299
-	// * Implements #423
+	// * Implements https://github.com/ericniebler/stl2/issues/423
 	//
 	namespace detail {
 		template <class T>
@@ -170,9 +166,6 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// Readable [readable.iterators]
-	// Not to spec: Disables the "Experimental additional tests"
-	// See https://github.com/ericniebler/stl2/issues/239
-	// Additional changes from P0547
 	//
 	template <class I>
 	concept bool Readable =
@@ -201,9 +194,6 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// Writable [iterators.writable]
-	// Not to spec, but getting closer.
-	// See https://github.com/ericniebler/stl2/issues/339
-	// and https://github.com/ericniebler/stl2/issues/381
 	//
 	template <class Out, class R>
 	concept bool Writable =
@@ -310,8 +300,6 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// iter_swap
-	// Not to spec
-	// See https://github.com/ericniebler/stl2/issues/242
 	//
 	namespace __iter_swap {
 		// Poison pill for iter_swap. (See the detailed discussion at
@@ -382,8 +370,6 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// IndirectlySwappable [commonalgoreq.indirectlyswappable]
-	// Not to spec
-	// See https://github.com/ericniebler/stl2/issues/241
 	//
 
 	template <class I1, class I2 = I1>
@@ -568,8 +554,7 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// OutputIterator [iterators.output]
-	// Not to spec:
-	// adds requirement on *i++ from P0541.
+	//
 	template <class I, class T>
 	concept bool OutputIterator =
 		Iterator<I> &&
@@ -587,8 +572,6 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// InputIterator [iterators.input]
-	// Not to spec: No requirements on i++
-	// See http://github.com/ericniebler/stl2/issues/232
 	//
 	template <class I>
 	concept bool InputIterator =
diff --git a/include/stl2/detail/iterator/counted_iterator.hpp b/include/stl2/detail/iterator/counted_iterator.hpp
index ab78d9e40..8fafeb7c5 100644
--- a/include/stl2/detail/iterator/counted_iterator.hpp
+++ b/include/stl2/detail/iterator/counted_iterator.hpp
@@ -23,7 +23,6 @@
 #include <stl2/detail/iterator/operations.hpp>
 
 STL2_OPEN_NAMESPACE {
-	// Not to spec: All members constexpr per P0579
 	Iterator{I}
 	class counted_iterator {
 		Iterator{O} friend class counted_iterator;
@@ -76,8 +75,6 @@ STL2_OPEN_NAMESPACE {
 			--cnt();
 			return *this;
 		}
-		// Not to spec:
-		// https://github.com/ericniebler/stl2/issues/232
 		constexpr decltype(auto) operator++(int) {
 			STL2_EXPECT(cnt() > 0);
 			--cnt();
@@ -129,8 +126,6 @@ STL2_OPEN_NAMESPACE {
 			return current()[n];
 		}
 
-		// Not to spec
-		// https://github.com/ericniebler/stl2/issues/245
 		friend constexpr rvalue_reference_t<I>
 		iter_move(const counted_iterator& i)
 			noexcept(noexcept(__stl2::iter_move(i.current())))
@@ -154,7 +149,6 @@ STL2_OPEN_NAMESPACE {
 		using type = iterator_category_t<I>;
 	};
 
-	// Not to spec: All operators constexpr per P0579
 	template <class I1, class I2>
 		requires Common<I1, I2>
 	constexpr bool operator==(
@@ -230,14 +224,12 @@ STL2_OPEN_NAMESPACE {
 		return x + n;
 	}
 
-	// Not to spec: constexpr per P0579
 	template <Iterator I>
 	constexpr auto make_counted_iterator(I i, difference_type_t<I> n)
 	STL2_NOEXCEPT_RETURN(
 		counted_iterator<I>{std::move(i), n}
 	)
 
-	// Not to spec: constexpr per P0579
 	Iterator{I}
 	constexpr void advance(counted_iterator<I>& i, difference_type_t<I> n)
 	noexcept(noexcept(__stl2::advance(std::declval<I&>(), n)))
@@ -247,7 +239,6 @@ STL2_OPEN_NAMESPACE {
 		i.cnt() -= n;
 	}
 
-	// Not to spec: constexpr per P0579
 	RandomAccessIterator{I}
 	constexpr void advance(counted_iterator<I>& i, difference_type_t<I> n)
 	STL2_NOEXCEPT_RETURN(
diff --git a/include/stl2/detail/iterator/increment.hpp b/include/stl2/detail/iterator/increment.hpp
index ffe76d789..c692774ac 100644
--- a/include/stl2/detail/iterator/increment.hpp
+++ b/include/stl2/detail/iterator/increment.hpp
@@ -27,8 +27,6 @@ STL2_OPEN_NAMESPACE {
 	// * Workaround https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78173; it is
 	//   necessary to guard the requires clause of the "fallback" specialization
 	//   to prevent hard errors for pointers to incomplete types.
-	// * Omit the extraneous is_array specialization.
-	//   See https://github.com/ericniebler/stl2/issues/243
 	//
 	namespace detail {
 		template <class T>
diff --git a/include/stl2/detail/iterator/insert_iterators.hpp b/include/stl2/detail/iterator/insert_iterators.hpp
index c339b94e7..beec83a9f 100644
--- a/include/stl2/detail/iterator/insert_iterators.hpp
+++ b/include/stl2/detail/iterator/insert_iterators.hpp
@@ -153,8 +153,6 @@ STL2_OPEN_NAMESPACE {
 		insert_iterator& operator++() {
 			return *this;
 		}
-		// Not to spec:
-		// https://github.com/ericniebler/stl2/issues/232
 		insert_iterator& operator++(int) {
 			return *this;
 		}
diff --git a/include/stl2/detail/iterator/istreambuf_iterator.hpp b/include/stl2/detail/iterator/istreambuf_iterator.hpp
index 6106c2a34..a76702124 100644
--- a/include/stl2/detail/iterator/istreambuf_iterator.hpp
+++ b/include/stl2/detail/iterator/istreambuf_iterator.hpp
@@ -31,8 +31,7 @@ STL2_OPEN_NAMESPACE {
 	}
 
 	// Not to spec:
-	// * requirements are implicit.
-	//   See https://github.com/ericniebler/stl2/issues/246)
+	// * Implements https://github.com/ericniebler/stl2/issues/246
 	//
 	template <class charT, class traits = std::char_traits<charT>>
 	requires
diff --git a/include/stl2/detail/iterator/move_iterator.hpp b/include/stl2/detail/iterator/move_iterator.hpp
index d4d7890f3..460a0036a 100644
--- a/include/stl2/detail/iterator/move_iterator.hpp
+++ b/include/stl2/detail/iterator/move_iterator.hpp
@@ -99,34 +99,6 @@ STL2_OPEN_NAMESPACE {
 				static_cast<void>(++current_)
 			)
 
-			// Not to spec
-			// Experimental support for move_iterator post-increment
-			// BUGBUG doesn't correctly handle when decltype(current_++)
-			// is a reference.
-			using __postinc_t = std::decay_t<decltype(current_++)>;
-			Readable{R}
-			struct __proxy {
-				using value_type = __stl2::value_type_t<R>;
-				R __tmp;
-				constexpr decltype(auto) operator*()
-				STL2_NOEXCEPT_RETURN(
-					__stl2::iter_move(__tmp)
-				)
-				friend constexpr decltype(auto) iter_move(const __proxy& that)
-				STL2_NOEXCEPT_RETURN(
-					__stl2::iter_move(that.__tmp)
-				)
-			};
-
-#if STL2_WORKAROUND_GCC_69096
-			template <class = void>
-#endif // STL2_WORKAROUND_GCC_69096
-			constexpr auto post_increment()
-			noexcept(noexcept(__proxy<__postinc_t>{current_++}))
-			requires !ForwardIterator<I> && Readable<__postinc_t> {
-				return __proxy<__postinc_t>{current_++};
-			}
-
 			constexpr void prev()
 			noexcept(noexcept(--current_))
 			requires BidirectionalIterator<I>
@@ -180,10 +152,6 @@ STL2_OPEN_NAMESPACE {
 		};
 	}
 
-	// Not to spec:
-	// * uses iter_move in operator* (See https://github.com/ericniebler/stl2/issues/244)
-	// * hooks iter_move and iter_swap (See https://github.com/ericniebler/stl2/issues/245)
-	// * constexpr per P0579
 	InputIterator{I}
 	using move_iterator = basic_iterator<__move_iterator::cursor<I>>;
 
@@ -192,7 +160,6 @@ STL2_OPEN_NAMESPACE {
 		using type = input_iterator_tag;
 	};
 
-	// Not to spec: constexpr per P0579
 	StrictTotallyOrderedWith{I1, I2}
 	constexpr bool
 	operator<(const move_iterator<I1>& a, const move_iterator<I2>& b)
@@ -201,7 +168,6 @@ STL2_OPEN_NAMESPACE {
 			__move_iterator::access::current(__stl2::get_cursor(b))
 	)
 
-	// Not to spec: constexpr per P0579
 	StrictTotallyOrderedWith{I1, I2}
 	constexpr bool
 	operator>(const move_iterator<I1>& a, const move_iterator<I2>& b)
@@ -209,7 +175,6 @@ STL2_OPEN_NAMESPACE {
 		b < a
 	)
 
-	// Not to spec: constexpr per P0579
 	StrictTotallyOrderedWith{I1, I2}
 	constexpr bool
 	operator<=(const move_iterator<I1>& a, const move_iterator<I2>& b)
@@ -217,7 +182,6 @@ STL2_OPEN_NAMESPACE {
 		!(b < a)
 	)
 
-	// Not to spec: constexpr per P0579
 	StrictTotallyOrderedWith{I1, I2}
 	constexpr bool
 	operator>=(const move_iterator<I1>& a, const move_iterator<I2>& b)
@@ -225,7 +189,6 @@ STL2_OPEN_NAMESPACE {
 		!(a < b)
 	)
 
-	// Not to spec: constexpr per P0579
 	template <class I>
 	requires
 		InputIterator<__f<I>>
@@ -234,7 +197,6 @@ STL2_OPEN_NAMESPACE {
 		move_iterator<__f<I>>{std::forward<I>(i)}
 	)
 
-	// Not to spec: constexpr per P0579
 	Semiregular{S}
 	class move_sentinel : detail::ebo_box<S, move_sentinel<S>> {
 		friend __move_iterator::access;
@@ -267,7 +229,6 @@ STL2_OPEN_NAMESPACE {
 		{ return box_t::get(); }
 	};
 
-	// Not to spec: constexpr per P0579
 	template <class S>
 	requires
 		Semiregular<__f<S>>
diff --git a/include/stl2/detail/iterator/operations.hpp b/include/stl2/detail/iterator/operations.hpp
index 99dae4b9a..e50d31263 100644
--- a/include/stl2/detail/iterator/operations.hpp
+++ b/include/stl2/detail/iterator/operations.hpp
@@ -19,7 +19,6 @@
 
 ///////////////////////////////////////////////////////////////////////////
 // Iterator operations [iterator.operations]
-// Not to spec: All constexpr per P0579.
 STL2_OPEN_NAMESPACE {
 	// advance
 	namespace __advance {
diff --git a/include/stl2/detail/iterator/ostream_iterator.hpp b/include/stl2/detail/iterator/ostream_iterator.hpp
index bb65bf940..7ccd46a2f 100644
--- a/include/stl2/detail/iterator/ostream_iterator.hpp
+++ b/include/stl2/detail/iterator/ostream_iterator.hpp
@@ -64,8 +64,6 @@ STL2_OPEN_NAMESPACE {
 		ostream_iterator& operator++() noexcept {
 			return *this;
 		}
-		// Not to spec:
-		// https://github.com/ericniebler/stl2/issues/232
 		ostream_iterator& operator++(int) noexcept {
 			return *this;
 		}
diff --git a/include/stl2/detail/iterator/ostreambuf_iterator.hpp b/include/stl2/detail/iterator/ostreambuf_iterator.hpp
index 93c32b52c..a9b0541a4 100644
--- a/include/stl2/detail/iterator/ostreambuf_iterator.hpp
+++ b/include/stl2/detail/iterator/ostreambuf_iterator.hpp
@@ -23,8 +23,6 @@
 #include <stl2/detail/iterator/default_sentinel.hpp>
 
 STL2_OPEN_NAMESPACE {
-	// Not to spec:
-	// * Extension: satisfies EqualityComparable and Sentinel<default_sentinel>
 	template <class charT, class traits = std::char_traits<charT>>
 	class ostreambuf_iterator {
 	public:
@@ -35,9 +33,6 @@ STL2_OPEN_NAMESPACE {
 		using streambuf_type = std::basic_streambuf<charT, traits>;
 
 		constexpr ostreambuf_iterator() noexcept = default;
-		constexpr ostreambuf_iterator(default_sentinel) noexcept
-		: ostreambuf_iterator{}
-		{}
 		STL2_CONSTEXPR_EXT ostreambuf_iterator(ostream_type& s) noexcept
 		: sbuf_(s.rdbuf()) {}
 		STL2_CONSTEXPR_EXT ostreambuf_iterator(streambuf_type* s) noexcept
@@ -56,32 +51,12 @@ STL2_OPEN_NAMESPACE {
 		ostreambuf_iterator& operator++() noexcept {
 			return *this;
 		}
-		// Not to spec:
-		// https://github.com/ericniebler/stl2/issues/232
 		ostreambuf_iterator& operator++(int) noexcept {
 			return *this;
 		}
 		bool failed() const noexcept {
 			return sbuf_ != nullptr;
 		}
-		friend bool operator==(ostreambuf_iterator a, ostreambuf_iterator b) noexcept {
-			return a.sbuf_ == b.sbuf_;
-		}
-		friend bool operator!=(ostreambuf_iterator a, ostreambuf_iterator b) noexcept {
-			return !(a == b);
-		}
-		friend bool operator==(ostreambuf_iterator a, default_sentinel) noexcept {
-			return a.sbuf_ == nullptr;
-		}
-		friend bool operator!=(ostreambuf_iterator a, default_sentinel b) noexcept {
-			return !(a == b);
-		}
-		friend bool operator==(default_sentinel, ostreambuf_iterator b) noexcept {
-			return b.sbuf_ == nullptr;
-		}
-		friend bool operator!=(default_sentinel a, ostreambuf_iterator b) noexcept {
-			return !(a == b);
-		}
 	private:
 		detail::raw_ptr<streambuf_type> sbuf_{nullptr};
 	};
diff --git a/include/stl2/detail/iterator/reverse_iterator.hpp b/include/stl2/detail/iterator/reverse_iterator.hpp
index 068d0fd83..0fbd6380e 100644
--- a/include/stl2/detail/iterator/reverse_iterator.hpp
+++ b/include/stl2/detail/iterator/reverse_iterator.hpp
@@ -132,14 +132,9 @@ STL2_OPEN_NAMESPACE {
 		};
 	}
 
-	// Not to spec:
-	// * Customizes iter_move and iter_swap.
-	//   See https://github.com/ericniebler/stl2/issues/245.
-	// * constexpr per P0579
 	BidirectionalIterator{I}
 	using reverse_iterator = basic_iterator<__reverse_iterator::cursor<I>>;
 
-	// Not to spec: constexpr per P0579
 	StrictTotallyOrderedWith{I1, I2}
 	constexpr bool operator<(
 		const reverse_iterator<I1>& x, const reverse_iterator<I2>& y)
@@ -148,7 +143,6 @@ STL2_OPEN_NAMESPACE {
 			__reverse_iterator::access::current(__stl2::get_cursor(y))
 	)
 
-	// Not to spec: constexpr per P0579
 	StrictTotallyOrderedWith{I1, I2}
 	constexpr bool operator>(
 		const reverse_iterator<I1>& x, const reverse_iterator<I2>& y)
@@ -156,7 +150,6 @@ STL2_OPEN_NAMESPACE {
 		y < x
 	)
 
-	// Not to spec: constexpr per P0579
 	StrictTotallyOrderedWith{I1, I2}
 	constexpr bool operator<=(
 		const reverse_iterator<I1>& x, const reverse_iterator<I2>& y)
@@ -164,7 +157,6 @@ STL2_OPEN_NAMESPACE {
 		!(y < x)
 	)
 
-	// Not to spec: constexpr per P0579
 	StrictTotallyOrderedWith{I1, I2}
 	constexpr bool operator>=(
 		const reverse_iterator<I1>& x, const reverse_iterator<I2>& y)
@@ -172,7 +164,6 @@ STL2_OPEN_NAMESPACE {
 		!(x < y)
 	)
 
-	// Not to spec: constexpr per P0579
 	template <class I>
 	requires BidirectionalIterator<__f<I>>
 	constexpr auto make_reverse_iterator(I&& i)
diff --git a/include/stl2/detail/range/concepts.hpp b/include/stl2/detail/range/concepts.hpp
index f48d32a7f..bb2c491d1 100644
--- a/include/stl2/detail/range/concepts.hpp
+++ b/include/stl2/detail/range/concepts.hpp
@@ -149,7 +149,6 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// OutputRange [ranges.output]
-	// Not to spec: value category sensitive.
 	//
 	template <class R, class T>
 	concept bool OutputRange =
diff --git a/include/stl2/detail/range/primitives.hpp b/include/stl2/detail/range/primitives.hpp
index 43748e161..adbf05376 100644
--- a/include/stl2/detail/range/primitives.hpp
+++ b/include/stl2/detail/range/primitives.hpp
@@ -42,14 +42,12 @@ STL2_OPEN_NAMESPACE {
 		)
 	}
 
-	// Not to spec: constexpr per P0579
 	Range{R}
 	constexpr difference_type_t<iterator_t<R>> distance(R&& r)
 	STL2_NOEXCEPT_RETURN(
 		__stl2::distance(__stl2::begin(r), __stl2::end(r))
 	)
 
-	// Not to spec: constexpr per P0579
 	SizedRange{R}
 	constexpr difference_type_t<iterator_t<R>> distance(R&& r)
 	STL2_NOEXCEPT_RETURN(
diff --git a/include/stl2/detail/swap.hpp b/include/stl2/detail/swap.hpp
index 227981ae3..cac6072b8 100644
--- a/include/stl2/detail/swap.hpp
+++ b/include/stl2/detail/swap.hpp
@@ -23,8 +23,7 @@
 STL2_OPEN_NAMESPACE {
 	///////////////////////////////////////////////////////////////////////////
 	// exchange [utility.exchange]
-	// Not to spec: constexpr
-	// See https://github.com/ericniebler/stl2/322
+	//
 	template <class T, class U = T>
 	requires
 		MoveConstructible<T> && Assignable<T&, U>
diff --git a/include/stl2/detail/tagged.hpp b/include/stl2/detail/tagged.hpp
index 8465693b0..d463cc9a6 100644
--- a/include/stl2/detail/tagged.hpp
+++ b/include/stl2/detail/tagged.hpp
@@ -94,8 +94,6 @@ STL2_OPEN_NAMESPACE {
 	///////////////////////////////////////////////////////////////////////////
 	// tagged [taggedtup.tagged]
 	// Not to spec:
-	// * constexpr per P0579
-	// * Implements https://github.com/ericniebler/stl2/issues/172
 	// * Implements https://github.com/ericniebler/stl2/issues/363
 	// * Implements https://github.com/ericniebler/stl2/issues/364
 	// * Implements https://github.com/ericniebler/stl2/issues/418
diff --git a/include/stl2/type_traits.hpp b/include/stl2/type_traits.hpp
index f5ce8aeb5..3770a87b3 100644
--- a/include/stl2/type_traits.hpp
+++ b/include/stl2/type_traits.hpp
@@ -179,8 +179,6 @@ STL2_OPEN_NAMESPACE {
 	struct common_reference<T, U, V, W...>
 	: common_reference<common_reference_t<T, U>, V, W...> {};
 
-	// Not to spec
-	// See https://github.com/ericniebler/stl2/issues/311
 	template <class T, class U>
 	concept bool CommonReference =
 		requires {
@@ -200,8 +198,7 @@ STL2_OPEN_NAMESPACE {
 
 	///////////////////////////////////////////////////////////////////////////
 	// Common [concepts.lib.corelang.common]
-	// Not to spec
-	// See https://github.com/ericniebler/stl2/issues/311
+	//
 	template <class T, class U>
 	concept bool Common =
 		requires {
diff --git a/test/concepts/object.cpp b/test/concepts/object.cpp
index 2ef6082e5..8fad5a911 100644
--- a/test/concepts/object.cpp
+++ b/test/concepts/object.cpp
@@ -276,7 +276,6 @@ CONCEPT_ASSERT(!models::CopyConstructible<nonmovable &&>);
 CONCEPT_ASSERT(models::CopyConstructible<const nonmovable &>);
 CONCEPT_ASSERT(!models::CopyConstructible<const nonmovable &&>);
 
-// https://github.com/ericniebler/stl2/issues/301
 struct not_mutable_ref {
 	not_mutable_ref() = default;
 	not_mutable_ref(const not_mutable_ref&) = default;
@@ -341,11 +340,7 @@ CONCEPT_ASSERT(models::DefaultConstructible<std::initializer_list<int>>);
 
 CONCEPT_ASSERT(models::Constructible<int*>);
 CONCEPT_ASSERT(models::DefaultConstructible<int*>);
-
-// https://github.com/ericniebler/stl2/issues/301
 CONCEPT_ASSERT(!models::Constructible<int&, long&>);
-
-// https://github.com/ericniebler/stl2/issues/310
 CONCEPT_ASSERT(!models::Movable<int&&>);
 
 int main() {}
diff --git a/test/iterator/move_iterator.cpp b/test/iterator/move_iterator.cpp
index ef8537ad3..314f25fef 100644
--- a/test/iterator/move_iterator.cpp
+++ b/test/iterator/move_iterator.cpp
@@ -218,19 +218,6 @@ void test_proxy_iterator() {
 		CHECK(A::move_count == N);
 		CHECK(ranges::equal(vec2, ranges::ext::take_exactly_view<ranges::ext::iota_view<int>>{0, N}, std::equal_to<>{}));
 		CHECK(ranges::equal(vec, ranges::ext::repeat_n_view<int>{-1, N}, std::equal_to<>{}));
-
-		first = ranges::make_move_iterator(proxy_iterator<A>{ranges::data(vec)});
-		std::iota(vec.begin(), vec.end(), 0);
-		vec2.clear();
-		A::clear();
-		while (first != last) // Test post-increment
-			*out++ = *first++;
-
-		CHECK(ranges::size(vec2) == N);
-		CHECK(A::copy_count == std::size_t{0});
-		CHECK(A::move_count == 2*N);
-		CHECK(ranges::equal(vec2, ranges::ext::take_exactly_view<ranges::ext::iota_view<int>>{0, N}, std::equal_to<>{}));
-		CHECK(ranges::equal(vec, ranges::ext::repeat_n_view<int>{-1, N}, std::equal_to<>{}));
 	}
 
 	{
diff --git a/test/iterator/ostreambuf_iterator.cpp b/test/iterator/ostreambuf_iterator.cpp
index c2c70fd47..9384b5da0 100644
--- a/test/iterator/ostreambuf_iterator.cpp
+++ b/test/iterator/ostreambuf_iterator.cpp
@@ -37,16 +37,13 @@ namespace {
 int main() {
 	using I = ostreambuf_iterator<char>;
 	static_assert(models::OutputIterator<I, const char&>);
-	static_assert(models::Sentinel<default_sentinel, I>);
-	static_assert(models::Common<I, default_sentinel>);
-	static_assert(std::is_same<I, common_type_t<I, default_sentinel>>());
 
 	{
 		static const char hw[] = "Hello, world!";
 		auto hw_range = ext::make_range(__stl2::begin(hw), __stl2::end(hw) - 1);
 		std::ostringstream os;
 		auto r = ::copy(hw_range, I{os});
-		CHECK(r.out() != default_sentinel{});
+		CHECK(r.out().failed());
 		::check_equal(os.str(), hw_range);
 	}