The content_type tag can be used to make the web server send back the contents with the desired Content-Type in the HTTP header.
By default every web page is send back as '_text/html_'.
As an example, the RSS feed requires it content type to be set as '_text/xml_' for the browsers to properly recognize the feed. The following snippet does the job -
<cms:content_type 'text/xml' />
Please see Core Concepts - RSS Feeds for an example of the usage of this tag.
The desired content type. Some example values are '_text/xml_', '_text/plain_', '_text/css_', '_image/gif_', '_application/pdf_' and '_application/zip_'.
This tag is self-closing and does not set any variables of its own.