By default the templating system pairs by name so index.tcl is paired with index.adp. You can override this but I've never had much luck with that. You can place files in the filesystem with paths like that those created with site map and override index.tcl and index.adp, but it's both or none. It would be nice if the request processor would allow you to override just index.adp so you could change the look without changing the code.
The form package is slightly better because you can specify a form template in the form tag. You still have to write code but it just seams cleaner to me.
Now that I say this I guess fixing the first would also allow forms to have different templates since the form template is in the adp file.
