Tag Metadata in Feeds

2008 Aug 25, 10:13

As noted previously, my page consists of the aggregation of my various feeds and in working on that code recently it was again brought to my attention that everyone has different ways of representing tag metadata in feeds. I made up a list of how my various feed sources represent tags and list that data here so that it might help others in the future.

Tag markup from various sources
Source	Feed Type	Tag Markup Scheme	One Tag Per Element	Tag Scheme URI	Human / Machine Names	Example Markup
LiveJournal	Atom	atom:category	yes	no	no	, (source)
LiveJournal	RSS 2.0	rss2:category	yes	no	no	`technical` (soure)
WordPress	RSS 2.0	rss2:category	yes	no	no	, (source)
Delicious	RSS 1.0	dc:subject	no	no	no	`photosynth photos 3d tool` (source)
Delicious	RSS 2.0	rss2:category	yes	yes	no	`domain="http://delicious.com/SequelGuy/"> hulu` (source)
Flickr	Atom	atom:category	yes	yes	no	`term="seattle" scheme="http://www.flickr.com/photos/tags/" />` (source)
Flickr	RSS 2.0	media:category	no	yes	no	`scheme="urn:flickr:tags"> seattle washington baseball mariners` (source)
YouTube	RSS 2.0	media:category	no	no	no	`label="Tags"> bunny rabbit yawn cadbury` (source)
LibraryThing	RSS 2.0	No explicit tag metadata.	no	no	no	n/a, (source)

Tag markup scheme
Tag Markup Scheme	Notes	Example
Atom Category atom:category `xmlns:atom="http://www.w3.org/2005/Atom"`	category/@term Required category name. category/@scheme Optional IRI id'ing the categorization scheme. category/@label Optional human readable category name.	`term="catName" scheme="tag:deletethis.net,2008:tagscheme" label="category name in human readable format"/>`
RSS 2.0 category rss2:category empty namespace	category/@domain Optional string id'ing the categorization scheme. category/text() Required category name. The value of the element is a forward-slash-separated string that identifies a hierarchic location in the indicated taxonomy. Processors may establish conventions for the interpretation of categories.	`domain="tag:deletethis.net,2008:tagscheme"> MSFT`
Yahoo Media RSS Module category media:category `xmlns:media="http://search.yahoo.com/mrss/"`	category/text() Required category name. category/@domain Optional string id'ing the categorization scheme.	`scheme="http://dmoz.org" label="Ace Ventura - Pet Detective"> Arts/Movies/Titles/A/Ace_Ventura_Series/Ace_Ventura_-_Pet_Detective`
Dublin Core subject dc:subject `xmlns:dc="http://purl.org/dc/elements/1.1/"`	subject/text() Required category name. Typically, the subject will be represented using keywords, key phrases, or classification codes. Recommended best practice is to use a controlled vocabulary.	`humor`

Update 2009-9-14: Added WordPress to the Tag Markup table and namespaces to the Tag Markup Scheme table.

Tag Metadata in Feeds - Dave's Blog

Tag Metadata in Feeds