In RSS Profile research, I analyzed how frequently RSS core elements and namespace elements appear in feeds.
Here's the compiled stats for item elements. Part one covered channel element usage.
The full report reveals that the most popular namespace element in RSS items is dc:creator from the Dublin Core namespace, which appeared in 42.7 percent of the feeds.
The second-most common is wfw:commentRss from the Well-Formed Web namespace, appearing in 34.3 percent. (This total includes wfw:commentRSS, a common miscapitalization of the element name.)
All core elements were found in at least 5 percent of the feeds surveyed with the exception of source, which appeared in 3.0 percent.
The following item elements were found in 1,933 RSS 2.0 feeds, which were chosen because they appear in OPML subscription lists published on the web. The quantity and percentage columns refer to how many feeds contained the element at least once. Parent-child relationships are indicated by hyphens ("-") in the element names. Namespace elements are indicated by colons (":").
| Element | Quantity | Percentage |
| item-description | 1865 | 96.48% |
| item-title | 1845 | 95.45% |
| item-link | 1833 | 94.83% |
| item-guid | 1661 | 85.93% |
| item-pubDate | 1616 | 83.60% |
| item-category | 921 | 47.65% |
| item-comments | 846 | 43.77% |
| item-dc:creator | 826 | 42.73% |
| item-wfw:commentRss | 662 | 34.25% |
| item-slash:comments | 528 | 27.32% |
| item-content:encoded | 252 | 13.04% |
| item-feedburner:origLink | 223 | 11.54% |
| item-dc:date | 205 | 10.61% |
| item-author | 176 | 9.11% |
| item-dc:subject | 138 | 7.14% |
| item-enclosure | 110 | 5.69% |
| item-wfw:comment | 103 | 5.33% |
| item-source | 59 | 3.05% |
| item-trackback:ping | 53 | 2.74% |
| item-body | 35 | 1.81% |
| item-lj:security | 30 | 1.55% |
| item-pingback:server | 28 | 1.45% |
| item-pingback:target | 28 | 1.45% |
| item-feedburner:awareness | 27 | 1.40% |
| item-cc:license | 22 | 1.14% |
| item-media:content | 22 | 1.14% |
| item-media:credit | 19 | 0.98% |
| item-media:text | 19 | 0.98% |
| item-topix:comments | 17 | 0.88% |
| item:atom-updated | 15 | 0.78% |
| item-lj:mood | 13 | 0.67% |
| item-lj:music | 13 | 0.67% |
| item-mscom:contentType | 13 | 0.67% |
| item-mscom:headlineImage | 13 | 0.67% |
| item-mscom:simpleDate | 13 | 0.67% |
| item-mscom:attribute | 12 | 0.62% |
| item-mscom:headlineIcon | 12 | 0.62% |
| item-itms:album | 11 | 0.57% |
| item-itms:albumLink | 11 | 0.57% |
| item-itms:albumPrice | 11 | 0.57% |
| item-itms:artist | 11 | 0.57% |
| item-itms:artistLink | 11 | 0.57% |
| item-itms:coverArt | 11 | 0.57% |
| item-itms:releasedate | 11 | 0.57% |
| item-itms:rights | 11 | 0.57% |
| item-pheedo:origLink | 9 | 0.47% |
| item-itunes:author | 8 | 0.41% |
| item:ent:cloud | 7 | 0.36% |
| item-ent:cloud-ent:topic | 7 | 0.36% |
| item-jf:modificationDate | 7 | 0.36% |
| item-jf:replyCount | 7 | 0.36% |
| item-dc:date.Taken | 6 | 0.31% |
| item-itunes:explicit | 6 | 0.31% |
| item-itunes:summary | 6 | 0.31% |
| item-taxo:topics | 6 | 0.31% |
| item-taxo:topics-rdf:Bag | 6 | 0.31% |
| item-taxo:topics-rdf:bag-rdf:li | 6 | 0.31% |
| item-atom:summary | 5 | 0.26% |
| item-contentType | 5 | 0.26% |
| item-creator | 5 | 0.26% |
| item-geo:lat | 5 | 0.26% |
| item-geo:long | 5 | 0.26% |
| item-itunes:duration | 5 | 0.26% |
| item-itunes:keywords | 5 | 0.26% |
| item-itunes:subtitle | 5 | 0.26% |
| item-georss:point | 4 | 0.21% |
| item-includedComments:comment-collection | 4 | 0.21% |
| item-itms:rank | 4 | 0.21% |
| item-feedburner:origEnclosureLink | 3 | 0.16% |
| item-itunes:block | 3 | 0.16% |
| item-content:format | 2 | 0.10% |
| item-itms:song | 2 | 0.10% |
| item-itms:songLink | 2 | 0.10% |
| item-subject | 2 | 0.10% |
| item-author:name | 1 | 0.05% |
| item:cf:itemRss | 1 | 0.05% |
| item-dc:contributor | 1 | 0.05% |
| item-dc:publisher | 1 | 0.05% |
| item-dc:rights | 1 | 0.05% |
| item-dcterms:isReferencedBy | 1 | 0.05% |
| item-dcterms:modified | 1 | 0.05% |
| item-dWBlogs:comments | 1 | 0.05% |
| item-icbm:latitude | 1 | 0.05% |
| item-icbm:longitude | 1 | 0.05% |
| item-itms:featureArt | 1 | 0.05% |
| item-live:type | 1 | 0.05% |
| item-live:typeLabel | 1 | 0.05% |
| item-media:category | 1 | 0.05% |
| item-media:thumbnail | 1 | 0.05% |
| item-media:title | 1 | 0.05% |
| item-msn:type | 1 | 0.05% |
| item-rb:guid | 1 | 0.05% |
| item-rb:source | 1 | 0.05% |
| item-rb:source_author | 1 | 0.05% |
| item-rb:source_feed_url | 1 | 0.05% |
| item-rb:source_published_date | 1 | 0.05% |
| item-rb:source_url | 1 | 0.05% |
| item-rb:via_link | 1 | 0.05% |
| item-trackback:about | 1 | 0.05% |
| item-wiki:diff | 1 | 0.05% |
| item-wiki:history | 1 | 0.05% |
| item-wiki:importance | 1 | 0.05% |
| item-wiki:status | 1 | 0.05% |
| item-wiki:username | 1 | 0.05% |
| item-wiki:version | 1 | 0.05% |
| item-wordzilla:id | 1 | 0.05% |
