2.1.134 [HTML5:2014] Section 126.96.36.199 Markup declaration open state
V0308: A non-HTML namespace CDATA section is not consumed properly and does not switch state
The specification states:
... Markup declaration open state ... Otherwise, if there is an adjusted current node and it is not an element in the HTML namespace and the next seven characters are a case-sensitive match for the string "[CDATA[" (the five uppercase letters "CDATA" with a U+005B LEFT SQUARE BRACKET character before and after), then consume those characters and switch to the CDATA section state.
All document modes (All versions)
A non-HTML namespace CDATA section is not consumed properly and does not switch state.