[html5] Validator.nu’s (X)HTML5 Validator does not validate XHTML5

Jorge . chocolate.camera at gmail.com
Mon Aug 28 03:09:51 PDT 2017

In fact, “About this service” at https://about.validator.nu/#presets
does document the service as having presets for “XHTML5
(experimental)” and “XHTML5+ARIA, SVG 1.1 plus MathML 2.0
(experimental)”, but that is apparently not true now.

On Mon, Aug 28, 2017 at 12:04 PM, Jorge . <chocolate.camera at gmail.com> wrote:
> Validator.nu (X)HTML5 Validator at https://html5.validator.nu
> validates only HTML5, not XHTML5, despite its name, when attempting to
> do so via direct input (Text Field).
> Tested with this markup:
> <?xml version="1.0" encoding="UTF-8"?>
> <!DOCTYPE html>
> <html xmlns="http://www.w3.org/1999/xhtml">
>    <head>
>       <meta charset="UTF-8"/>
>       <title>My title</title>
>    </head>
>    <body>
>    </body>
> </html>
> The submission form does not have an option to forcibly request XHTML5
> validation instead of HTML5. Even when the markup is preceded by the
> XML declaration (which nevertheless is purportedly not necessary if
> contents are UTF-8), the validator reports the very declaration as an
> error:
>> Error: Saw <?. Probable cause: Attempt to use an XML processing instruction in HTML. (XML processing instructions are not supported in HTML.)
> revealing that even with such markup it is validating HTML5 instead of XHTML5.
> The generic validator at https://validator.nu used to have a preset or
> parser (cannot remember) specifically for XHTML5, but not anymore
> either it seems.

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