Revised 2005 proposal for meta-data

Michel Fortin michel.fortin at
Fri Dec 29 15:14:22 EST 2006

Le 2006-12-29 à 7:53, Andrea Censi a écrit :

> This is the revised 2005 proposal for meta-data, much more in detail:






> I wait for comments.

{#myid .class1 .class2}
{id=myid class=class1 class=class2}
{id=myid class="class1 class2"}

In my current implementation, the first and the last one are
equivalent, but not the one in the middle: the second class will
override the first one. I think it's more coherent to reserve the
magic to the ".class" syntax. And overriding may also be a useful
feature in some circumstances where you have a remotely-defined class
you want to replace completly:

## Header ## {boo class="override"}

{boo}: .boo style=color:green;font-weight:bold

- - -


Why not "attribute definitions" and "attribute references" in the
same spirit as link definitions and link references? "Tag" makes me
think of HTML tags.

- - -

"An unquoted value must not start with a double quote, and may
contain everything except whitespace"

You need an exception for the closing brace when the attribute is
defined inline, and I would allow attribute values to be enclosed in
single quotes too, just like HTML and XML permits it.

- - -

"Identifiers must begin with a letter ([A-Za-z]) and may be followed
by any number of letters, digits ([0-9]), hyphens (-), underscores
(_), colons (:), and periods (.)."

This seems too restrictive. First, id and class in HTML and XML both
allow much more Unicode characters, and second: what should happen
when someone introduce an invalid character somewhere? Do we pass it
unmodified, try to correct it, or skip it completely? I'd go with the
former, except for the cases where it would destroy the markup like
having an attribute name with `>` or `=`.

- - -

"Question: should we allow whitespace at the sides of = in key/value

I don't think so, not if we're mixing them with attribute references
and magic shortcuts. I don't think this would be very readable:

[link][1]{.class hreflang = fr ref}

{ref}: lang = en .class

- - -

"Question: should : be a synonym for = in attributes list."

While it would certainly be nice, I think it's a better idea to have
an HTML-like syntax to define HTML attributes. Beside, it's not very
clear what will happen when you have a space after the colon. Compare

[link][1]{.class hreflang: fr ref}

{ref}: lang: en .class

with this:

[link][1]{.class hreflang=fr ref}

{ref}: lang=en .class

I think the key/value association is clearer in the second example.

- - -

Other considerations: allowing arbitrary attribute values on span
elements may pose problem to the current parsers. For instance, this


is hard to parse correctly, because if the link reference [1] is not
defined, the link becomes pure text and `coco` must be changed to a
code span, while if the link is defined then `coco` is an attribute
and must not be changed to a code span. The only way to get this
correctly is to parse all the span expressions together, creating a
"real" parser as some have suggested.

I think this problem is inexistent with the way block elements are

Michel Fortin
michel.fortin at

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