<PackageReference Include="System.Security.Permissions" Version="10.0.3" />

System.Security.Permissions.IsolatedStoragePermissionAttribute

Allows security actions for IsolatedStoragePermission to be applied to code using declarative security.
namespace System.Security.Permissions { public abstract class IsolatedStoragePermissionAttribute : CodeAccessSecurityAttribute { public long UserQuota { get; set; } public IsolatedStorageContainment UsageAllowed { get; set; } protected IsolatedStoragePermissionAttribute(SecurityAction action); } }