diff --git a/Extensions b/Extensions
index e9ed863..26d6985 160000
--- a/Extensions
+++ b/Extensions
@@ -1 +1 @@
-Subproject commit e9ed8637e3df9c142136ba64b8f1e7b11e44f85c
+Subproject commit 26d6985fccb345f1f3bce799953bf046e01b0d86
diff --git a/System.Polyfills/System.Polyfills.props b/System.Polyfills/System.Polyfills.props
new file mode 100644
index 0000000..c6dfb7f
--- /dev/null
+++ b/System.Polyfills/System.Polyfills.props
@@ -0,0 +1,7 @@
+<Project>
+  <ItemGroup>
+    <Using Include="System.Runtime.CompilerServices" />
+    <Using Include="System.Diagnostics.CodeAnalysis.StringSyntaxAttribute" Alias="StringSyntax" />
+    <Using Include="System.Diagnostics.CodeAnalysis.StringSyntaxAttribute" Alias="StringSyntaxAttribute" />
+  </ItemGroup>
+</Project>
diff --git a/System.Polyfills/System.Polyfills.targets b/System.Polyfills/System.Polyfills.targets
index 9827214..dbe15fb 100644
--- a/System.Polyfills/System.Polyfills.targets
+++ b/System.Polyfills/System.Polyfills.targets
@@ -7,10 +7,6 @@
     <DefineConstants Condition="'$(TargetFramework)' == 'netstandard2.0'">$(DefineConstants);NOTNETSTANDARD21ORGREATER</DefineConstants>
     <DefineConstants Condition="$(TargetFramework.StartsWith('netstandard1')) OR $(TargetFramework.StartsWith('netcore'))">$(DefineConstants);NOTNETSTANDARD20ORGREATER</DefineConstants>
   </PropertyGroup>
-  <ItemGroup Condition="'$(MSBuildProjectName)' != 'System.Private.CoreLib.Polyfills'">
-    <Using Include="System.Runtime.CompilerServices" />
-    <Using Include="System.Diagnostics.CodeAnalysis.StringSyntaxAttribute" Alias="StringSyntax" Condition="$(DefineConstants.Contains('NOTNET70ORGREATER'))" />
-  </ItemGroup>
 
   <!-- <UsingTask TaskName="CheckForDuplicateItems" AssemblyFile="$(MicrosoftNETBuildTasksAssembly)" /> -->
 
diff --git a/System.Polyfills/System.Runtime.CompilerServices/IsExternalInit.cs b/System.Polyfills/System.Runtime.CompilerServices/IsExternalInit.cs
index 9f5c449..a793654 100644
--- a/System.Polyfills/System.Runtime.CompilerServices/IsExternalInit.cs
+++ b/System.Polyfills/System.Runtime.CompilerServices/IsExternalInit.cs
@@ -1,16 +1,25 @@
-#if !NET6_0_OR_GREATER
+#if NET5_0_OR_GREATER
+
+[assembly: System.Runtime.CompilerServices.TypeForwardedTo(
+    typeof(System.Runtime.CompilerServices.IsExternalInit)
+)]
+
+#else
+
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
-
 using System.ComponentModel;
 
-namespace System.Runtime.CompilerServices
-{
-    /// <summary>
-    /// Reserved to be used by the compiler for tracking metadata. This class
-    /// should not be used by developers in source code.
-    /// </summary>
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public static class IsExternalInit { }
-}
+namespace System.Runtime.CompilerServices;
+
+// https://github.com/dotnet/runtime/blob/v8.0.0/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/IsExternalInit.cs
+
+/// <summary>
+/// Reserved to be used by the compiler for tracking metadata.
+/// This class should not be used by developers in source code.
+/// </summary>
+[EditorBrowsable(EditorBrowsableState.Never)]
+public // polyfill!
+static class IsExternalInit { }
+
 #endif
diff --git a/System.Polyfills/System/DateOnly.cs b/System.Polyfills/System/DateOnly.cs
index e84226b..e955060 100644
--- a/System.Polyfills/System/DateOnly.cs
+++ b/System.Polyfills/System/DateOnly.cs
@@ -400,7 +400,7 @@ public static DateOnly Parse(
         /// <exception cref="FormatException"><paramref name="s"/> does not contain a valid string representation of a date.</exception>
         public static DateOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] ReadOnlySpan<char> format,
             IFormatProvider? provider = default,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -419,7 +419,7 @@ public static DateOnly ParseExact(
         /// <exception cref="FormatException"><paramref name="s"/> does not contain a valid string representation of a date.</exception>
         public static DateOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] string[] formats
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] string[] formats
         ) => ParseExact(s, formats, null, DateTimeStyles.None);
 
         /// <summary>
@@ -436,7 +436,7 @@ public static DateOnly ParseExact(
         /// <exception cref="FormatException"><paramref name="s"/> does not contain a valid string representation of a date.</exception>
         public static DateOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] string[] formats,
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] string[] formats,
             IFormatProvider? provider,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -479,7 +479,7 @@ public static DateOnly Parse(
         /// <exception cref="FormatException"><paramref name="s"/> does not contain a valid string representation of a date.</exception>
         public static DateOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] ReadOnlySpan<char> format,
             IFormatProvider? provider = default,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -500,7 +500,7 @@ public static DateOnly ParseExact(
         /// <exception cref="FormatException"><paramref name="s"/> does not contain a valid string representation of a date.</exception>
         public static DateOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] string[] formats
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] string[] formats
         ) => ParseExact(s, formats, null, DateTimeStyles.None);
 
         /// <summary>
@@ -517,7 +517,7 @@ public static DateOnly ParseExact(
         /// <exception cref="FormatException"><paramref name="s"/> does not contain a valid string representation of a date.</exception>
         public static DateOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] string[] formats,
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] string[] formats,
             IFormatProvider? provider,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -565,7 +565,7 @@ public static DateOnly Parse(
         /// <exception cref="FormatException"><paramref name="s"/> does not contain a valid string representation of a date.</exception>
         public static DateOnly ParseExact(
             string s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] string format
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] string format
         ) => ParseExact(s, format, null, DateTimeStyles.None);
 
         /// <summary>
@@ -582,7 +582,7 @@ public static DateOnly ParseExact(
         /// <exception cref="FormatException"><paramref name="s"/> does not contain a valid string representation of a date.</exception>
         public static DateOnly ParseExact(
             string s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] string format,
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] string format,
             IFormatProvider? provider,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -601,7 +601,7 @@ public static DateOnly ParseExact(
         /// <exception cref="FormatException"><paramref name="s"/> does not contain a valid string representation of a date.</exception>
         public static DateOnly ParseExact(
             string s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] string[] formats
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] string[] formats
         ) => ParseExact(s, formats, null, DateTimeStyles.None);
 
         /// <summary>
@@ -618,7 +618,7 @@ public static DateOnly ParseExact(
         /// <exception cref="FormatException"><paramref name="s"/> does not contain a valid string representation of a date.</exception>
         public static DateOnly ParseExact(
             string s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] string[] formats,
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] string[] formats,
             IFormatProvider? provider,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -686,7 +686,7 @@ out DateOnly result
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] ReadOnlySpan<char> format,
             out DateOnly result
         ) => TryParseExact(s, format, null, DateTimeStyles.None, out result);
 
@@ -707,7 +707,7 @@ out DateOnly result
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] ReadOnlySpan<char> format,
             IFormatProvider? provider,
             DateTimeStyles style,
             out DateOnly result
@@ -731,7 +731,7 @@ out DateOnly result
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.DateOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.DateOnlyFormat)]
                 string?[]? formats,
             out DateOnly result
         ) => TryParseExact(s, formats, null, DateTimeStyles.None, out result);
@@ -752,7 +752,7 @@ out DateOnly result
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.DateOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.DateOnlyFormat)]
                 string?[]? formats,
             IFormatProvider? provider,
             DateTimeStyles style,
@@ -821,7 +821,7 @@ out DateOnly result
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] ReadOnlySpan<char> format,
             out DateOnly result
         ) => TryParseExact(s, format, null, DateTimeStyles.None, out result);
 
@@ -842,7 +842,7 @@ out DateOnly result
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] ReadOnlySpan<char> format,
             IFormatProvider? provider,
             DateTimeStyles style,
             out DateOnly result
@@ -872,7 +872,7 @@ out var dateTime
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.DateOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.DateOnlyFormat)]
                 string?[]? formats,
             out DateOnly result
         ) => TryParseExact(s, formats, null, DateTimeStyles.None, out result);
@@ -893,7 +893,7 @@ out DateOnly result
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.DateOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.DateOnlyFormat)]
                 string?[]? formats,
             IFormatProvider? provider,
             DateTimeStyles style,
@@ -963,7 +963,7 @@ out DateOnly result
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             [NotNullWhen(true)] string? s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] string? format,
+            [NotNullWhen(true), @StringSyntax(StringSyntax.DateOnlyFormat)] string? format,
             out DateOnly result
         ) => TryParseExact(s, format, null, DateTimeStyles.None, out result);
 
@@ -983,7 +983,7 @@ out DateOnly result
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             [NotNullWhen(true)] string? s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] string? format,
+            [NotNullWhen(true), @StringSyntax(StringSyntax.DateOnlyFormat)] string? format,
             IFormatProvider? provider,
             DateTimeStyles style,
             out DateOnly result
@@ -1006,7 +1006,7 @@ out DateOnly result
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             [NotNullWhen(true)] string? s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.DateOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.DateOnlyFormat)]
                 string?[]? formats,
             out DateOnly result
         ) => TryParseExact(s, formats, null, DateTimeStyles.None, out result);
@@ -1026,7 +1026,7 @@ out DateOnly result
         /// otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             [NotNullWhen(true)] string? s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.DateOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.DateOnlyFormat)]
                 string?[]? formats,
             IFormatProvider? provider,
             DateTimeStyles style,
@@ -1063,7 +1063,7 @@ out DateOnly result
         /// <param name="format">A standard or custom date format string.</param>
         /// <returns>A string representation of value of the current <see cref="DateOnly"/> object as specified by <paramref name="format"/>.</returns>
         public string ToString(
-            [@StringSyntax(@StringSyntaxAttribute.DateOnlyFormat)] string? format
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] string? format
         )
         {
             if (string.IsNullOrEmpty(format))
@@ -1089,7 +1089,7 @@ public string ToString(
         /// <param name="provider">An object that supplies culture-specific formatting information.</param>
         /// <returns>A string representation of value of the current <see cref="DateOnly"/> object as specified by format and provider.</returns>
         public string ToString(
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)] string? format,
+            [@StringSyntax(StringSyntax.DateOnlyFormat)] string? format,
             IFormatProvider? provider
         )
         {
@@ -1117,7 +1117,7 @@ public string ToString(
         public bool TryFormat(
             Span<char> destination,
             out int charsWritten,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)]
+            [@StringSyntax(StringSyntax.DateOnlyFormat)]
                 ReadOnlySpan<char> format = default(ReadOnlySpan<char>),
             IFormatProvider? provider = null
         )
@@ -1144,7 +1144,7 @@ public bool TryFormat(
         public bool TryFormat(
             Span<char> destination,
             out int charsWritten,
-            [@StringSyntax(StringSyntaxAttribute.DateOnlyFormat)]
+            [@StringSyntax(StringSyntax.DateOnlyFormat)]
                 ReadOnlySpan<char> format = default(ReadOnlySpan<char>),
             IFormatProvider? provider = null
         )
diff --git a/System.Polyfills/System/TimeOnly.cs b/System.Polyfills/System/TimeOnly.cs
index 478cd4c..90cd239 100644
--- a/System.Polyfills/System/TimeOnly.cs
+++ b/System.Polyfills/System/TimeOnly.cs
@@ -481,7 +481,7 @@ public static TimeOnly Parse(
         /// as specified by <paramref name="format"/>, <paramref name="provider"/> and <paramref name="style"/>.</returns>
         public static TimeOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] ReadOnlySpan<char> format,
             IFormatProvider? provider = default,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -499,7 +499,7 @@ public static TimeOnly ParseExact(
         /// as specified by one of <paramref name="formats"/>.</returns>
         public static TimeOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string[] formats
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] string[] formats
         ) => ParseExact(s, formats, null, DateTimeStyles.None);
 
         /// <summary>
@@ -515,7 +515,7 @@ public static TimeOnly ParseExact(
         /// as specified by <paramref name="provider"/>, <paramref name="style"/>, and one of <paramref name="formats"/>.</returns>
         public static TimeOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string[] formats,
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] string[] formats,
             IFormatProvider? provider,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -555,7 +555,7 @@ public static TimeOnly Parse(
         /// as specified by <paramref name="format"/>, <paramref name="provider"/> and <paramref name="style"/>.</returns>
         public static TimeOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] ReadOnlySpan<char> format,
             IFormatProvider? provider = default,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -575,7 +575,7 @@ public static TimeOnly ParseExact(
         /// as specified by one of <paramref name="formats"/>.</returns>
         public static TimeOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string[] formats
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] string[] formats
         ) => ParseExact(s, formats, null, DateTimeStyles.None);
 
         /// <summary>
@@ -591,7 +591,7 @@ public static TimeOnly ParseExact(
         /// as specified by <paramref name="provider"/>, <paramref name="style"/>, and one of <paramref name="formats"/>.</returns>
         public static TimeOnly ParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string[] formats,
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] string[] formats,
             IFormatProvider? provider,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -637,7 +637,7 @@ public static TimeOnly Parse(
         /// as specified by <paramref name="format"/>.</returns>
         public static TimeOnly ParseExact(
             string s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string format
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] string format
         ) => ParseExact(s, format, null, DateTimeStyles.None);
 
         /// <summary>
@@ -655,7 +655,7 @@ public static TimeOnly ParseExact(
         /// as specified by <paramref name="format"/>, <paramref name="provider"/> and <paramref name="style"/>.</returns>
         public static TimeOnly ParseExact(
             string s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string format,
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] string format,
             IFormatProvider? provider,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -673,7 +673,7 @@ public static TimeOnly ParseExact(
         /// as specified by one of <paramref name="formats"/>.</returns>
         public static TimeOnly ParseExact(
             string s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string[] formats
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] string[] formats
         ) => ParseExact(s, formats, null, DateTimeStyles.None);
 
         /// <summary>
@@ -689,7 +689,7 @@ public static TimeOnly ParseExact(
         /// as specified by <paramref name="provider"/>, <paramref name="style"/>, and one of <paramref name="formats"/>.</returns>
         public static TimeOnly ParseExact(
             string s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string[] formats,
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] string[] formats,
             IFormatProvider? provider,
             DateTimeStyles style = DateTimeStyles.None
         )
@@ -751,7 +751,7 @@ out TimeOnly result
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] ReadOnlySpan<char> format,
             out TimeOnly result
         ) => TryParseExact(s, format, null, DateTimeStyles.None, out result);
 
@@ -770,7 +770,7 @@ out TimeOnly result
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] ReadOnlySpan<char> format,
             IFormatProvider? provider,
             DateTimeStyles style,
             out TimeOnly result
@@ -792,7 +792,7 @@ out TimeOnly result
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.TimeOnlyFormat)]
                 string?[]? formats,
             out TimeOnly result
         ) => TryParseExact(s, formats, null, DateTimeStyles.None, out result);
@@ -811,7 +811,7 @@ out TimeOnly result
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.TimeOnlyFormat)]
                 string?[]? formats,
             IFormatProvider? provider,
             DateTimeStyles style,
@@ -874,7 +874,7 @@ out TimeOnly result
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] ReadOnlySpan<char> format,
             out TimeOnly result
         ) => TryParseExact(s, format, null, DateTimeStyles.None, out result);
 
@@ -893,7 +893,7 @@ out TimeOnly result
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] ReadOnlySpan<char> format,
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] ReadOnlySpan<char> format,
             IFormatProvider? provider,
             DateTimeStyles style,
             out TimeOnly result
@@ -921,7 +921,7 @@ out var dateTime
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.TimeOnlyFormat)]
                 string?[]? formats,
             out TimeOnly result
         ) => TryParseExact(s, formats, null, DateTimeStyles.None, out result);
@@ -940,7 +940,7 @@ out TimeOnly result
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             ReadOnlySpan<char> s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.TimeOnlyFormat)]
                 string?[]? formats,
             IFormatProvider? provider,
             DateTimeStyles style,
@@ -1007,7 +1007,7 @@ out TimeOnly result
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             [NotNullWhen(true)] string? s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string? format,
+            [NotNullWhen(true), @StringSyntax(StringSyntax.TimeOnlyFormat)] string? format,
             out TimeOnly result
         ) => TryParseExact(s, format, null, DateTimeStyles.None, out result);
 
@@ -1026,7 +1026,7 @@ out TimeOnly result
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             [NotNullWhen(true)] string? s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string? format,
+            [NotNullWhen(true), @StringSyntax(StringSyntax.TimeOnlyFormat)] string? format,
             IFormatProvider? provider,
             DateTimeStyles style,
             out TimeOnly result
@@ -1048,7 +1048,7 @@ out TimeOnly result
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             [NotNullWhen(true)] string? s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.TimeOnlyFormat)]
                 string?[]? formats,
             out TimeOnly result
         ) => TryParseExact(s, formats, null, DateTimeStyles.None, out result);
@@ -1067,7 +1067,7 @@ out TimeOnly result
         /// <returns><see langword="true"/> if the <paramref name="s"/> parameter was converted successfully; otherwise, <see langword="false"/>.</returns>
         public static bool TryParseExact(
             [NotNullWhen(true)] string? s,
-            [NotNullWhen(true), @StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)]
+            [NotNullWhen(true), @StringSyntax(StringSyntax.TimeOnlyFormat)]
                 string?[]? formats,
             IFormatProvider? provider,
             DateTimeStyles style,
@@ -1104,7 +1104,7 @@ out TimeOnly result
         /// <param name="format">A standard or custom time format string.</param>
         /// <returns>A string representation of value of the current <see cref="TimeOnly"/> object as specified by <paramref name="format"/>.</returns>
         /// <remarks>The accepted standard formats are 'r', 'R', 'o', 'O', 't' and 'T'. </remarks>
-        public string ToString([@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string? format)
+        public string ToString([@StringSyntax(StringSyntax.TimeOnlyFormat)] string? format)
         {
             if (string.IsNullOrEmpty(format))
             {
@@ -1131,7 +1131,7 @@ public string ToString([@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] str
         /// as specified by <paramref name="format"/> and <paramref name="provider"/>.</returns>
         /// <remarks>The accepted standard formats are 'r', 'R', 'o', 'O', 't' and 'T'. </remarks>
         public string ToString(
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)] string? format,
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)] string? format,
             IFormatProvider? provider
         )
         {
@@ -1160,7 +1160,7 @@ public string ToString(
         public bool TryFormat(
             Span<char> destination,
             out int charsWritten,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)]
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)]
                 ReadOnlySpan<char> format = default(ReadOnlySpan<char>),
             IFormatProvider? provider = null
         )
@@ -1187,7 +1187,7 @@ public bool TryFormat(
         public bool TryFormat(
             Span<char> destination,
             out int charsWritten,
-            [@StringSyntax(StringSyntaxAttribute.TimeOnlyFormat)]
+            [@StringSyntax(StringSyntax.TimeOnlyFormat)]
                 ReadOnlySpan<char> format = default(ReadOnlySpan<char>),
             IFormatProvider? provider = null
         )