### Repositioning HTML for CSS and javascript links {#html-post}

Modern HTML commonly uses  CSS  and   Javascript.  This  requires <link>
elements in the HTML <head> element or  <script> elements in the <body>.
Unfortunately this seriously harms re-using HTML DCG rules as components
as each of these components  may  rely   on  their  own  style sheets or
JavaScript code. We added a `mailing'   system to reposition and collect
fragments of HTML. This is  implemented by html_post//2, html_receive//1
and html_receive//2.

	* [[html_post//2]]
	* [[html_receive//1]]
	* [[html_receive//2]]

The library predefines the receiver channel  =head=   at  the end of the
=head= element for all pages that  write   the  html =head= through this
library. The following  code  can  be   used  anywhere  inside  an  HTML
generating rule to demand a javascript in the header:

==
js_script(URL) -->
	html_post(head, script([ src(URL),
				 type('text/javascript')
			       ], [])).
==

This  mechanism  is  also  exploited  to  add  XML  namespace  (=xmlns=)
declarations to the (outer) =html= element using xhml_ns//2:

	* [[xhtml_ns//2]]
