[whatwg] Suggest making <dt> and <dd> valid in <ol>

Ian Yang ian.html at gmail.com
Mon Jul 16 00:02:42 PDT 2012

2012/7/16 Ian Hickson <ian at hixie.ch>

> On Sat, 14 Jul 2012, Ian Yang wrote:
> > Recently I was involved in a project. One of its pages has a special
> > content which is like a "life cycle". There are several stages in the
> > cycle, each stage has a term followed by some text describing the term.
> > Let's take the life cycle of butterfly for example:
> >
> > Egg
> > A white egg.
> >
> > Caterpillar
> > The egg hatches into a caterpillar. The caterpillar eats and grows a
> > tremendous amount.
> >
> > Pupa
> > The caterpillar forms a hard outer shell. Inside the shell, the
> caterpillar
> > changes into a butterfly.
> >
> > Butterfly
> > Butterflies live for only a short time. They will fly, mate, and
> reproduce.
> > The female lays an egg that was fertilized by the male.
> >
> > By seeing such contents, we usually code it using definition list
> > (<dl>). At first, I was thinking the same idea. But then I realized that
> > stages in a life cycle should be regarded as ordered contents. So
> > ordered list (<ol>) would be more appropriate.
> <ol> and <dl> would both be fine here. I'd probably go with <ol>, because
> it's a list of states, each of which has a name, rather than a list of
> names, but both are reasonable.
> With <ol>, I'd probably write:
>    <ol>
>     <li><dfn>Egg</dfn>: A white egg.
>     <li><dfn>Caterpillar</dfn>: The egg hatches...
> ...and so on.

Thanks. That use looks fine, yet I'm a bit confused now. What's the
difference between *using definition list (<dl>)* and *using ordered list (
<ol>) with <dfn> inside of it*? And how could we determine when to use

> If we could make <dt> and <dd> being not restricted to <dl> only, but
> > could also exist in <ol>, the problem will be solved perfectly.
> It's not clear that there's a problem to be solved. :-)
> (Also, there are parsing issues that make changing this area of the spec
> be rather fraught with peril.)

Yeah, I had gave up that idea as it loses the meaning "definition list".

On Sat, 14 Jul 2012, Ian Yang wrote:
> >
> > Thanks for the info about the spec saying in <dl> the order of the list
> > of groups *may* be significant. However, what it says means a <dl>
> > itself is unable to tell whether its contents are unordered or ordered,
> > and we have to judge that by ourselves.
> Well, what it means is that a user agent can't randomly reorder a <dl>'s
> contents, as that would violate the rule that its rendering must
> faithfully represent the page's semantics. (The spec relies on this in
> several places to mark up English-prose equivalents of "switch statements"
> in its algorithms, for example.)
> > Comparing to <ul> and <ol> which themselves are able to tell whether
> > their contents are unordered and ordered, the <dl> itself being unable
> > to do that is, imho, disappointing.
> It's something we could add, but it's not clear that there's a compelling
> need for it. What is the use case for knowing that a <dl>'s contents can
> be arbitrarily reordered?

Well, I'm not sure if "user agent can't randomly reorder its contents"
equals to "the order of its content is important". If it does, some use
cases of <dl> such as FAQ may became incorrect as the order of contents of
FAQ is usually unimportant.

Ian Yang

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