System.Text.Encoding.CodePages by Microsoft

<PackageReference Include="System.Text.Encoding.CodePages" Version="8.0.0-preview.2.23128.3" />

 SupportedOSPlatformGuardAttribute

Annotates a custom guard field, property or method with a supported platform name and optional version. Multiple attributes can be applied to indicate guard for multiple supported platforms.
namespace System.Runtime.Versioning { [AttributeUsage(AttributeTargets.Method | AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = true, Inherited = false)] internal sealed class SupportedOSPlatformGuardAttribute : System.Runtime.Versioning.OSPlatformAttribute { public SupportedOSPlatformGuardAttribute(string platformName) : base(platformName) { } } }