dotnet-installer/scripts/Microsoft.DotNet.Cli.Build.Framework/Enumerations/BuildPlatform.cs

namespace Microsoft.DotNet.Cli.Build.Framework
{
    public enum BuildPlatform
    {
        Windows = 1,
        Unix = 2,
        Linux = 3,
        OSX = 4,
        Ubuntu = 5,
        CentOS = 6
    }
}