Theory question: U+000C in HTML 4.01

[Jukka K. Korpela]

This question is fairly theoretical (even for me), but it started to
puzzle me:

According to the SGML declaration for HTML 4.01, at
http://www.w3.org/TR/REC-html40/sgml...cl.html#h-20.1
the Form Feed character, U+000C (12 in decimal), is UNUSED, i.e. forbidden:

DESCSET 0 9 UNUSED
9 2 9
11 2 UNUSED

Yet, the prose of the specification discusses it as if it were an
allowed character. Section 9.1 White space says:

"In HTML, only the following characters are defined as white space
characters:

- ASCII space ( )
- ASCII tab (	)
- ASCII form feed ()
- Zero-width space (​)"

( http://www.w3.org/TR/REC-html40/struct/text.html#h-9.1 )

Is this just a slip in the SGML declaration, or in the prose? I'd
suppose the latter, since the formal rule was the same in HTML 3.2,
which did not mention U+000C at all in the prose. So when people wrote
the HTML 4.01 prose, they just didn't check what's in the formal
declaration.

The W3C validator and the WDG validator seem to report U+000C as an
error ("Non-SGML character number 12"), apparently playing by the SGML
declaration for HTML 4.01.

(XHTML, as XML in general, forbids U+000C explicitly. And U+000C is not
useful in HTML: it's just another whitespace character, not a page eject
character, as one might naively expect.)

[Benjamin Niemann]

Jukka K. Korpela wrote:

According to the SGML declaration for HTML 4.01, at
http://www.w3.org/TR/REC-html40/sgml...cl.html#h-20.1
the Form Feed character, U+000C (12 in decimal), is UNUSED, i.e.
forbidden:

DESCSET 0 9 UNUSED
9 2 9
11 2 UNUSED

Yet, the prose of the specification discusses it as if it were an
allowed character. Section 9.1 White space says:

"In HTML, only the following characters are defined as white space
characters:

- ASCII space ( )
- ASCII tab (	)
- ASCII form feed ()
- Zero-width space (​)"

( http://www.w3.org/TR/REC-html40/struct/text.html#h-9.1 )

Is this just a slip in the SGML declaration, or in the prose? I'd
suppose the latter, since the formal rule was the same in HTML 3.2,
which did not mention U+000C at all in the prose. So when people wrote
the HTML 4.01 prose, they just didn't check what's in the formal
declaration.

It certainly does not make much sense to allow the form feed in HTML. But it
is rather common to treat it as whitespace in languages where whitespace is
not significant (e.g. C), this seems to be some kind of traditional
convention. The CSS21 spec (I did not check the other CSS versions) does
also include it in its list of ws characters, so there seems to be _some_
consistency across the different specs.

I would bet (but not much money ;) that the authors added the form feed in
order to conform to some tradition, but forgot to think about the SGML
declaration.

And the form feed _could_ be used to manually prepare HTML source code for
printing, so it might be useful for one or two people on this planet.

--
Benjamin Niemann
Email: pink at odahoda dot de
WWW: http://www.odahoda.de/

[Benjamin Niemann]

Jukka K. Korpela wrote:

This question is fairly theoretical (even for me), but it started to
puzzle me:

btw: you are not the first one:
http://lists.w3.org/Archives/Public/...lSep/0131.html
But no one seems to care...

--
Benjamin Niemann
Email: pink at odahoda dot de
WWW: http://www.odahoda.de/