>>>First, thank you for the link to web.config transformation. I will read it.
>>>
>>>Mainly I need two different web.config files because each application (one in the Site and the other in Virtual Directory) should use a different Form for Form Authentication. That is, pages in one application should be authentication by form MyAuthen1.aspx and the other one by MyAuthen2.aspx. I am not sure that web.config transformation would allow that. But I will check.
>>
>>You could do that by adding a key in the web.config to identify the correct form.
>>Or, better, create a custom configuration and add a constant to the conditional compilation symbols (project properties/build tab)
>>e.g. enter USEFORM_A as a constant. Then in your code:

#ifdef USEFORM_A
>>//Load form a
>>#else
>>//Load form b
>>#endif

>>
>>
>
>I didn't realize the syntax of

#ifdef #else #endif

exists in Web.config of ASP.NET. It looks more like VFP stuff. But I will look for the pages explaining this.
>Thank you very much.

http://msdn.microsoft.com/en-us/library/yt3yck0x.aspx

Example of using the pre-defined DEBUG symbol. You can set the value on the Project/Build tab by ticking 'Define DEBUG constant'. If you look at the default 'Debug' and 'Release' configurations you will see that it is checked in Debug but not in Release (TRACE is checked for both) Any symbol you add in the textbox above will behave in the same way (you can define as many as you wish separated by a semicolon)