current syntax:

<font size="<!--#var font_size-->">

which is legal, would become:

<font size="<?ztml #var arg ?>">

which *not* valid XML...is it? That is, can you have markup inside markup?

I don't see any differences, current syntax is as (il)legal as "xml" syntax. But why don't ask the PHP3 guys (www.php.net) or and do it the same way. PHP3 uses also <?php ... ?>. Oliver