element "figure" & "figcaption" undefined

Dear W3C-Team,

by using html5-elements in a xhtml-document type like this:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html 
xmlns="http://www.w3.org/1999/xhtml">that means that I am obliged to 
delete / to remove the valid icon from this page
> http://www.feligrenowein.de/bestform.html
although this page is functioning without error with any browser? Thank 
you for your response in advance yours friendly & sencerely Dieter 
Offermann

Validating http://www.feligrenowein.de/bestform.html
Error [76]: "element X undefined"

-- 
Dieter Offermann
Bruststraße 49
64285 Darmstadt
Tel. 06151-424501

Received on Sunday, 27 December 2015 08:15:31 UTC