Compiler Error CS1529

A using clause must precede all other elements defined in the namespace except extern alias declarations

A using clause must appear first in a namespace.

Example

The following sample generates CS1529:

// CS1529.cs
namespace X
{
    namespace Subspace
    {
        using Microsoft;

        class SomeClass
        {
        };

        using Microsoft;      // CS1529, place before class definition
    }

    using System.Reflection;  // CS1529, place before namespace 'Subspace'
}

using System;                 // CS1529, place at the beginning of the file