XMLWriter in Perl, PHP and Tcl

Here's some information on XMLWriter.

It looks like popular XMLWriter implementations in PHP, Perl and Tcl just wrap the C library libxml2 (or older libxml) :
http://xmlsoft.org/index.html

For Perl, there's a CPAN XMLWriter :
http://search.cpan.org/~josephw/XML-Writer/

For PHP, there's an old PECL library that looks like it will work with older versions (4.x) of PHP :
http://pecl.php.net/package/xmlwriter

I used to use Tcl quite a bit 10 years ago, but have since lost touch. But there is a lot of Tcl used in embedded systems. Looks like TclXML is the relevant interface :
http://tclxml.sourceforge.net/