YEAH! Amazing! Big thanks,
OpenGeek!! So the final decision is:
1) At CMS i’m used for every Resource default ContentType: "text/html"
2) Wrote plugin, which firing ’OnWebPagePrerender’;
3) The plugin’s code is:
<?php
if (preg_match('|application/xhtml\+xml|i', $_SERVER['HTTP_ACCEPT']))
$modx->resource->ContentType->set('mime_type','application/xhtml+xml');
So, if the browser do not supports ContentType ’application/xhtml+xml’ (e.g. IE 5.5 - IE 8.0), header ’Content-Type’, would not be modified (so ’Content-Type: text/html’ will be send).
Otherwise header would be modified to ’Content-Type: application/xhtml+xml’.
It’s was necessary for me to using inline-svg.