asp, asp.NET, PHP are languages or technologies for processing scripts on
the server, and delivering the results of the processing to the browser as
HTML. FrontPage uses asp to process data to and from databases, since the
FrontPage extensions cannot do this.
FrontPage needs an .asp extension for the confirmation pages for its
database forms to keep things simple.
If you write your own scripts, you could use a .htm page - or any other
extension - for the confirmation page, provided the server supports the
technology or language used. And these confirmation pages can have any
content, including another form.