Does it? When I started validating (I don't remember if it was epubcheck or flightcrew, or both) I got an error with inline SVG and DTD and, as far as I know, the XHTML 1.1 doctype does not allow inline SVG
Have a look here:
http://www.daisy.org/epub/issues/cla...e-allowed-epub particularly at message #49
My understanding now is that DOCTYPE is not necessary, but if it's used it must be the right one for the content, and HTML+SVG is
not valid in the XHTML 1.1 DOCTYPE. So, if you are going to use them, either you must include a custom DOCTYPE, or just remove the line, as it's not needed anyway.