Comment by swiftcoder
7 hours ago
> If you do a 'view source' in Firefox on a completely valid XHTML 1.0/1.1 page, it'll redline the XML declaration like it's something wrong
Is the page actually being served as "application/xhtml+xml"? Most xhtml sites aren't, in which case the browser is indeed interpreting those as invalid declarations in a regular old html document
Those red squiggles on view-source: pages in Gecko all have title text with diagnostics. The message (errProcessingInstruction) in recent-ish releases is given as:
> Saw “<?”. Probable cause: Attempt to use an XML processing instruction in HTML. (XML processing instructions are not supported in HTML.)
If it’s served as XML, then view-source instead highlights the doctype line as an error (“Stray doctype.”).
I can confirm, I'm seeing this on my XHTML pages that are served as application/html+xml, that's a shame.