alternates-brainstorming

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Introduction

This page is to talk about alternates, that is, places where a user may be given several different items to choose amongst that at some logical level are considered equivalent. The best stawman so far is #6.

Discussion Participants

Editor

Authors

Interested Folks

  • Joshua Kinberg
  • Ernest Prabhakar

Brainstorms

Strawman 1

<fieldset>
 <a href="example.mp3" type="audio/mpeg">MP3 alternative</a>
 <a href="example.wav" type="audio/wav">WAV alternative</a>
 <a href="example.mov" type="video/quicktime">MOV alternative</a>
</fieldset>

XHTML Sample

Discussion

  • is legal but warps XHTML definitions -- David Janes
  • I think that is fieldset abuse -1 KevinMarks

Strawman 2

   <select id="entryN">
     <option value="example.mp3">MP3 alternative</option>
     <option value="example.mov">WAV alternative</option>
     <option value="example.wav">MOV alternative</option>
   </select>

XHTML Sample

Discussion

  • is legal but warps XHTML definitions -- David Janes
  • butt ugly, probably beyond redemption -- David Janes
  • the alternatives aren't clearly links -1 KevinMarks

Strawman 3

<div class="altgroup">
 <a class="alternate" href="example.mp3" type="audio/mpeg">MP3 alternative</a>
 <a class="alternate" href="example.wav" type="audio/wav">WAV alternative</a>
 <a class="alternate" href="example.mov" type="video/quicktime">MOV alternative</a>
</div>

Discussion

  • Looks better, but we have an existing rel="alternate" in HTML

Strawman 4 (lists)

An example of a list that expresses no preference. 

<ul class="altgroup">
 <li><a href="example.mp3" type="audio/mpeg">MP3 alternative</a></li>
 <li><a href="example.wav" type="audio/wav">WAV alternative</a></li>
 <li><a href="example.mov" type="video/quicktime">MOV alternative</a></li>
</ul>

An example of a list that expresses a preference (i.e. first is best, last is worst) 

<ol class="altgroup">
 <li><a href="example.mp3" type="audio/mpeg">MP3 alternative</a></li>
 <li><a href="example.wav" type="audio/wav">WAV alternative</a></li>
 <li><a href="example.mov" type="video/quicktime">MOV alternative</a></li>
</ol>

Discussion

  • this rocks, though I'm a little indifferent to altgroup. The only downside is that 'loosely coupled' alternates may not be covered; on the other hand, this may not be so much of an issue. We will know more from the examples -- David Janes
  • I like this a lot, and the ul/ol distinction is good, but the rel="alternate" should be there too.

Strawman 5 (lists + explicit alternator)

This varies #4, explicitly stating what is being alternated. Let's say we're trying to express "location". If there was no alternates, we'd just say: 

<a href="example.mp3" class="location">MP3</a>

Now, let's say that we have multiple choices. Here's what I think it should look like: 

<ol class="location alternates">
  <li>
    <a href="example.mp3" class="location">MP3</a>
    <br />
    I ripped this one using <a href="...">iTunes</a>
  </li>
  <li>
    <a href="example.wma" class="location">WMA</a>
    <br />
    I ripped this one using <a href="...">Windows Media</a>
  </li>
</ol>

Discussion

David Janes:

  • "alternates" indicates there's a bunch of choices to follow
  • "location" appears multiple times because ...
  • "location alternates" indicates we're _composing_ the alternates MF with "location"

Lucas Gonze:

  • I fiddled around with CSS and javascript to support this and found it was pretty easy to work with. That's a big plus.
  • A drawback is that it departs from existing idioms for microformats.
  • A plus is that the same method can be applied to other variants of the Alternates microformat. Let's say you have some MF that depends on a class "photo" to distinguish which one of multiple IMG elements is the alternate, you can declare the OL or UL with class="photo alternates".
  • Another plus is that the technique can extend out to more than one item per option, like if there must be both a photo and a location; that would be <ul class="photo location alternates" />
  • I have one real doubt. If we're inventing a new syntax to extend the Alternates MF even before the ink is dry, I'm not certain it is adding anything except a hint to help search engines understand the page. I have to think about that issue a bit more.

David Janes:

  • I love the fact that it can be applied to other MFs. For example, you could do something like this to express alternate vcards for the same person...
<ol class="vcard alternates">
  <li><div class="vcard">vcard 1</li>
  <li><div class="vcard">vcard 2</li>
</ol>
  • ... that said, it'd probably be best to run this past everyone else, as it does change the way parsing would happen. Perhaps it's only valid for inner elements?

Strawman 6 (lists + explicit alternator + using existing HTML idiom)

The idiom seems to apply to media files a lot, so bringing in rel=enclosure makes sense here. At the HTML level rel="alternate" is used for stating alternatives (normally on a <link>, but <link> and <a> have the same semantic), and type is applied to the links as a MIME type.

http://www.w3.org/TR/html4/struct/links.html#h-12.3

If you are listing alternatives, use a list

So for your examples, a possible model would be (OL is used to express ordered preference) 

<ol class="alternates">
 <li><a href="example.mp3" rel="enclosure alternate" type="audio/mpeg">MP3 alternative</a></li>
 <li><a href="example.wav" rel="enclosure alternate" type="audio/wav">WAV alternative</a></li>
 <li><a href="example.mov" rel="enclosure alternate" type="video/quicktime">MOV alternative</a></li>
</ol>

Following the links syntax, language alternatives can be expressed too (UL indicates no preference in order): 

<ul class="alternates">
 <li><a href="enexample.mp3" rel="enclosure alternate" type="audio/mpeg" hreflang="en">In English</a></li>
 <li><a href="esexample.mp3" rel="enclosure alternate" type="audio/mpeg" hreflang="es">En Espagnol</a></li>
 <li><a href="deexample.mp3" rel="enclosure alternate" type="audio/mpeg" hreflang="de">Auf Deutsch</a></li>
 </ul>

Discussion

Kevin Marks: I think this retains what you have, and brings it back in line with existing HTML practices. I have a stylistic nitpick about 'alternates' rather than 'alternatives' but as HTML has already gone the other way on that I can concede it. Is class="alternates" distinct enough to prevent false positives in looking for this structure?

DrErnie: What if there is no existing attribute for selecting against? Say I have both hi-res and low-res versions of a QuickTime movie available for streaming? Is there any appropriate way to hint/label that?

Kevin Marks: For streaming, I'd say use the built-in QuickTime Alternates mechanism that relies on detected bandwidth. I'd also say "don't use streaming, use fast-start download", and give the users a visible choice about which one to download (see The Cars trailer for one set of options).

See Also

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