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Re: Request for explanation: "the main element must not appear as a descendant of the td element" error message.

From: David Dorward <david@dorward.me.uk>
Date: Thu, 31 Jan 2019 09:14:54 +0000
To: "Jean-Pierre GAY" <jpg@temesis.com>
Cc: www-validator@w3.org
Message-ID: <70631774-17FD-4F85-8689-51E541E61145@dorward.me.uk>

On 30 Jan 2019, at 19:06, Jean-Pierre GAY wrote:

> I've got this error message: "the main element must not appear as a 
> descendant of the td element".

> However, nothing in the HTML specification indicates that " the main 
> element must not appear as a descendant of the td element": Content 
> model for td is flow content and parent content model expected for 
> main is also flow content (except for article, aside, footer, header 
> and nav). So, what is the meaning of this error message?

*Start stream of thought*

It looks like this is caused by this change: 

This does appear to contradict the HTML 5.2 specification: 

The WHAT WG spec says: 

> Contexts in which this element can be used:
> Where flow content is expected, but only if it is a hierarchically 
> correct main element.


> A hierarchically correct main element is one whose ancestor elements 
> are limited to html, body, div, form without an accessible name, and 
> autonomous custom elements. Each main element must be a hierarchically 
> correct main element.

  This agrees with the comment on the change to the validator:

> Allow only `html`, `body`, `div`, `form`, custom elements as `main` 
> ancestor

*End stream of thought*

The validator is comparing to the What WG Living HTML specification, and 
not the HTML 5.2 specification.

I suspect that the HTML 5.2 version is based on an older snapshot of 
What WG Living and it has changed in the meantime.

David Dorward
Received on Thursday, 31 January 2019 09:15:26 UTC

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