Media attribute for docbook referenced css?

Hi everyone

In this day and age where more users use small screens to read web
content, I have been looking for at possible media attribute to supply
to the output from the docbook stylesheets.

It is possible to supply more css file references in
<xsl:param
name="html.stylesheet">../../../globaLib/css/phone.css 
../../../globaLib/css/nmlDocbookUvmat.css
</xsl:param>

and, as I understand you may supply one (1)
<xsl:param name="html.stylesheet.type">text/css</xsl:param>
which would then apply to all the css files, I suppose.

I am looking for something like
<xsl:param name="html.stylesheet.media">only screen and (max-width: 640px)</xsl:param>
ie a media attribyte, which no-one has invented yet?

Ideally you would need n sets of
<xsl:param name="html.stylesheet">...</xsl:param>
<xsl:param name="html.stylesheet.type">...</xsl:param>
<xsl:param name="html.stylesheet.media">...</xsl:param>
one set per stylesheet.

Suitable for a change request?

Cheers