Re: How is this done?

[TT_Mark]

You’re dynamically altering with PHP as it is posting the information back from the form.

Reading and writing to files with PHP is actually quite easy, it could be that they have a template set up with a bunch of tags like {$doctype} that they do a find and replace based upon the postback from the form. Or it could be that they generate it all from scratch fopen() and file_get_contents() are two functions you may want to look into