RadChart has been replaced by RadHtmlChart, Telerik's client-side charting component. If you are considering RadChart for new development, examine the RadHtmlChart documentation and online demos first to see if it will fit your development needs. If you are already using RadChart in your projects, you can migrate to RadHtmlChart by following these articles: Migrating Series, Migrating Axes, Migrating Date Axes, Migrating Databinding, Features parity. Support for RadChart is discontinued as of Q3 2014, but the control will remain in the assembly so it can still be used. We encourage you to use RadHtmlChart for new development.
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 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.