XHTML
RadChart has been deprecated since Q3 2014 and is no longer recommended for use, as it does not support modern browsers. We strongly recommend using RadHtmlChart, Telerik's modern client-side charting component. To transition from RadChart to RadHtmlChart, refer to the following migration articles:
Explore the RadHtmlChart documentation and online demos to determine how it fits your development needs.
Compliance Level
Telerik RadChart now provides complete XHTML compliance.
The generated HTML output is fully XHTML 1.1 with the following exception:
Browsers don't fully support XHTML 1.1 compliant image maps, so when using charts with image maps the generated HTML is only XHTML 1.0 compliant.
XHTML
XHTML stands for EXtensible HyperText Markup Language: a stricter and cleaner version of HTML recommended by W3C (the World Wide Web Consortium). XHTML is the effective inheritor of HTML 4.01 and although it is almost identical to its predecessor it is aimed at replacing it.