“它”在哪里?来自ObjectSet. selectvalue的示例

productQuery1.SelectValue<Int32>("it.ProductID");

我怎么知道这里的"it"是什么意思?

来自MSDN文档的完整示例

using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    string queryString =
        @"SELECT VALUE product FROM 
            AdventureWorksEntities.Products AS product";
    ObjectQuery<Product> productQuery1 =
        new ObjectQuery<Product>(queryString,
            context, MergeOption.NoTracking);
    ObjectQuery<Int32> productQuery2 =
        productQuery1.SelectValue<Int32>("it.ProductID");
    foreach (Int32 result in productQuery2)
    {
        Console.WriteLine("{0}", result);
    }
}