If someone wanted to extend OPML into another domain, even if they got others to agree on their proposed type value and the new attributes added to support that type, there's nothing to stop a collision with somebody else choosing the same attribute names.
There also is nothing to stop the author of the OPML specification from opposing the new type.
It would be far easier to create a new XML format.
I love love love XML, but when I encounter an effort to use it to carry presentation like HTML alongside executable code -- such as Apache Jelly -- I regret the choices that brought me to that place in my life.
I wouldn't call OPML a good example of XML for reasons I detail elsewhere in the thread. But if you need a subscription list of feeds for import or export it's alright.
OPML is useful because people use it, but it was a bad design decision to store long blocks of HTML inside XML attributes instead of XML elements. Look at the escaped HTML inside these "text" attributes:
Because the HTML is stored in attributes, it can't be wrapped in a CDATA block. There's also no limit to how long the text can be.
OPML is also a moving target without a standard. Any time there's a desire to represent something new with the format, attributes are added without any public participation from existing implementers. The value of the "type" attribute on outline elements determines whether new arbitrary attributes can be present.
Because of this unorthodox extension process, the OPML format has become a catch-all for unrelated uses: outlines, blog posts, RSS/Atom subscription lists, programming source code, and more.
All of the uses could've been represented as XML formats. XML didn't need OPML for storing and transmitted arbitrary data. We already had XML for that.
The original thing OPML was created to do -- represent outlines -- is severely hampered by the fact there's no way to store the expansion state of collapsed nodes of an outline.
Atom is a great feed format with a rock-solid spec.
I wouldn't call it a weird mashup for WordPress to use atom:link in their RSS feeds. It does things no RSS element can do, such as allow a feed to identify its own URL.
For those who don't know, every WordPress site with an RSS feed also has an Atom feed available by adding "/atom" to the end of the RSS feed URL, such as this:
I think the inspiration was that an atom is a foundational building block of matter and a lot of things could be built with a well-specified universal feed format and publishing format.
The time spent debating names, disqualifying names, requalifying names and voting on names was like the battle of the newscasters on Anchorman. Pure carnage.
I wouldn't say that an Atom feed is an implementation of the "RSS concept." That muddies the water too much. Because RSS and Atom are distinct feed formats, calling an Atom feed "RSS" would confuse a lot of people.
Instead I'd say that Atom feeds and RSS feeds are each an implementation of the syndication concept.
As part of the RSS Advisory Board, I enjoyed the history lesson.
The W3C should keep publishing the RSS 2.0 specification along with the RSS 1.0 and Atom specifications in the documentation for its Feed Validation Service.
It can also republish the RSS Best Practices Profile that was created by the RSS Advisory Board, because it was released under the Creative Commons Attribution/Share Alike 2.0 license.
I'm Rogers Cadenhead, the chairman of the RSS Advisory Board.
What W3C is doing is correct. It is republishing our copy of the RSS specification under the terms of the Creative Commons Attribution/Share Alike license and using our preferred authorship credit: RSS Advisory Board with a link to https://www.rssboard.org/.
The RSS Advisory Board has published the RSS 2.0 specification for 20 years. Over that time we have revised it 10 times, mostly in minor ways such as to fix a broken link.
The board began publishing the spec under a Creative Commons Attribution/Share Alike license when Dave Winer was still a member. It is redistributable under the terms of that license forever.
Winer wrote this on his blog in 2003:
"On July 15, UserLand Software transferred ownership of its RSS 2.0 specification to the Berkman Center for Internet & Society at Harvard Law School.
"Berkman then placed a Creative Commons license on the spec, allowing it to be customized, excerpted and republished. ...
"The spec can circulate freely thanks to the Creative Commons."
The credit line on the specification has been unchanged since Aug. 12, 2006: "This document is authored by the RSS Advisory Board and is offered under the terms of the Creative Commons Attribution/Share Alike license, based on an original document published by the Berkman Center for Internet & Society."
We've never been asked to change that, by Dave Winer or anyone else.
Because of his new request for an attribution change, the credit line now reads, "This document is authored by the RSS Advisory Board and is offered under the terms of the Creative Commons Attribution/Share Alike license, based on an original document published by the Berkman Klein Center for Internet & Society authored by Dave Winer, founder of UserLand Software."
There should never be something about 'respect' when it comes to a specification.
When I publish anything on the web, do I have to give credit to Tim Berners-Lee each time?
A specification isn't a badge of honor, it's a useful tool, one among many. Other than clarification of who is currently authority for, and making changes to, a specification, there should be no names on any spec or standard.
Respect is also a useful tool. It reduces conflicts just as diplomacy reduces violence. Yes, respect can be set aside but, when you do, expect controversy.
Why would anyone want to invite unnecessary controversy when writing a spec?
Choosing a Mastodon instance is like signing up for an email provider. Email is decentralized and seems to be doing alright.
I picked an instance that was good-sized at 9,000 users with a focus I liked: indieweb.social. That gives me a Local feed of interesting indieweb-related content in addition to my Home feed of people I follow. I didn't have to trust my privacy to an anonymous activist. I know who is running the instance and support it via Patreon.
There also is nothing to stop the author of the OPML specification from opposing the new type.
It would be far easier to create a new XML format.