xmlhtmlxhtmldoctype

Does XHTML5 require a DOCTYPE/DTD?

I'm creating a language that translates to XML, and it doesn't support DOCTYPE/DTD. Can I use XHTML5 without having to specify <!DOCTYPE html>, or am I stuck with having to implement DOCTYPE/DTD? I'd rather not, mainly to avoid language complexity.

Solution

  • The WHATWG says:

    In the XML syntax, any doctype declaration may be used, or it may be omitted altogether.

    and also:

    The <!DOCTYPE html> definition is optional, but (...)

    And the W3C says:

    [The Document Type Declaration] may optionally be used within the XHTML syntax, but (...)

    so we can safely assume that the DOCTYPE declaration is optional.
    Also, a quick and dirty test shows that in the latest browsers, there is no discernible difference in handling files with or without a doctype declaration. As long as the file type is .xml or .xhtml.