While this may not be exactly the case with .ASP pages... I'm guessing it's pretty close....
Since dynamic pages like .ASP and PHP pages are made up of multiple "building block" files... not at all like an HTML page, the first line of the file (NOT the page... since there may be no single file .asp or php Web page) is the declaration of the type of page... .asp or php ... for example, here is how WordPress starts it's "index.php" pages:
<?php
/**
* @package WordPress
* @subpackage Default_Theme
*/
get_header(); ?>
so the first step is to declare that this is a .php page... then go get the "header" building block file .. OK, from the "header.php" file:
<?php
/**
* @package WordPress
* @subpackage Default_Theme
*/
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" <?php language_attributes(); ?>>
Declare the file type then put some HTML in....So it's a couple steps into the process of assembling a dynamic Web page before the DOCTYPE declaration is made. Yet since you never see any of the php... you might assume that the DOCTYPE was declared as the first line in the code.
Yet that is far from the truth.... and I'm pretty sure this is basically how .asp works also.
So if there is an error in the DOCTYPE declaration, take a look at your index or header (or whatever .asp is calling the first file). The actual HTML that displays on the page will be there.
Best wishes,
Adninjastrator
