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Consider a site about one's family tree.  It might have something like:
Consider a site about one's family tree.  It might have something like:
<source lang="html4strict">
I can trace my family back to  
I can trace my family back to <a href="http://en.wikipedia.org/wiki/William_I_of_England">William the conqueror.</a>
<a href="http://en.wikipedia.org/wiki/William_I_of_England">
  William the conqueror.
In these cases it would be useful to have @rel="ancestor", and perhaps a corresponding @rel="descendant".
In these cases it would be useful to have @rel="ancestor", and perhaps a corresponding @rel="descendant".

Revision as of 11:08, 28 November 2008

XFN Brainstorming


This page is for brainstorming about various uses and details of XFN, as well as collecting input for potential extensions.

Required Reading

Before participating in any XFN brainstorming please read and understand the following:

Note that all existing XFN values were based on research that showed real world sites that indicated such relationships explicitly via text and hyperlinks to other sites. Thus any new semantics or values will be more seriously considered if URLs demonstrating existing text labeling and hyperlinking behavior are provided.



Identity Consolidation

See rel-me and identity-consolidation.  

Indicating non-identity

I think we need a way to indicate that another page should not be consolidated into your identity. - KevinMarks

common name disambiguation

If you have a common name, creating a disambiguation page or pages to indicate which ones aren't you is useful for indexers and people alike. In fact there are examples of people already creating such a page and linking to pages that are not them. Real world use cases that would benefit:

accidental or malicious rel-me links

If someone accidentally or maliciously links to one of my pages with rel="me" it would be good to be able to actually deny the connection, rather than just passively not link back. See | the social graph API results for kevinmarks.com for examples. - KevinMarks

This appears to be more of a theoretical use case (as compared to the common name disambiguation) because the real world use is to simply not link back, and I don't think we should encourage people to add links to things that are not them, nor are they likely to, especially if it is a spammer/stalker/griefer that is linking to them. - Tantek

notme proposal

initial proposal: rel="notme", though very open to better suggestions.

Extending family relationships


The XFN: Background page says:

We considered adding "grandparent," but in the end dropped the term because it seemed unlikely to be used in the near future. It may appear in future versions of XFN.

Presumably the assumption is that a grandparent won't have a website, but:

To date, no real world examples have been documented, thus, per the microformats process, we should not complicate a format for a theoretical need. However, anyone that cares to pursue this may find some real world examples to document in the following web searches: "my grandpa's website", "my grandfather's website", "my grandma's website", "my grandmother's website". See also genealogy-examples.

ancestor descendant

Even if they don't maintain it themselves (or are deceased) there might be a URL that does a good job of representing a person.

Consider a site about one's family tree. It might have something like:

I can trace my family back to <a href="http://en.wikipedia.org/wiki/William_I_of_England">William the conqueror.</a>

In these cases it would be useful to have @rel="ancestor", and perhaps a corresponding @rel="descendant". -CiaranMc

See also: genealogy-brainstorming#Relationships

So far only a couple of (representative) real world examples (from just one site) have been provided, thus, per the microformats process, we should not complicate a format for a need clearly outside of the 80/20. Examples from Wikipedia: Winston Churchill, with list if ancestors, Queen Elizabeth II: refers to "Queen Victoria as [her] great-great-grandmother". See also genealogy-examples.

Simple Groups and Members

A very simple extension to XFN could enable decentralized group membership. E.g.

The relationships could be required bi-directional in order to confirm group membership, that is, both the individual must link to the group with rel="group" and the group must link to the individiual with rel="member" in order for the membership to be considered "true".

See also group-brainstorming for more on this including documentation of examples.

fans and followers

It's becoming a common aspect of many social networks (see list below) that you have unreciprocated and non-friend-based connections to people. These connections are particularly noteworthy where you don't really ever expect to have your connections reciprocated, but instead are similar to the idea of "rel-muse".

fan follower examples

Sites that have the semantic / implied-schema of "fan" or "follower")

possible inverse of fan terms

Brainstorm list of possible terms (for an inverse of fan/follower):

rejected fan follower terms


I would propose adding "rel-fan" or "rel-follower" to the collection of XFN values -- as being something like a "contact" or a "muse" but having a different purpose within the realm of social networking. Again, given that this is showing up in social networks like Pownce (fan), Twitter (follower), and that these words are becoming common, I wonder if it wouldn't make sense to even ditch rel-muse in favor of rel-follower and rel-fan (the former implying some kind of positive social stalking and the latter a kind of amiable appreciation for someone's work).

This fan/follower designation seems sorely lacking from Flickr where not everyone falls into either contact, friend or family... but in many cases, you just like someone's photos and want to be able to check in on them every now and again, similar to the way that people "follow" or "subscribe" to blog feeds... Someone who reads my blog feed could be considered a "follower" -- as in, "someone who follows my blog".

- Chris Messina

Chris, rel-fan or rel-follower would work for you to point to people who follow you, but the converse case is probably more useful, saying who you follow (eg blogroll case too). We need a good noun for that relationship that describes how you view them, that is less coloured than 'muse' currently is by being classified as romantic. rel-source or rel-influence maybe? Very hard to come up with a good noun.

Kevin Marks 12:57, 17 Aug 2007 (PDT)

  • Hence the existence of the HTML "rev" attribute. TobyInk 00:12, 25 Feb 2008 (PST)
    • The use of rev has been deprecated since authors nearly always get it wrong. Tantek 10:32, 6 Aug 2008 (PDT)
      • I'm not suggesting that we create a new microformat using rev — I'm pointing out that if we define rel=fan (for linking to your fans) then rev=fan "automatically pops into meaning". (Besides which the usually quoted evidence of rev being "confusing" to authors (i.e. Google's analysis) is flaky at best.) TobyInk 15:26, 6 Aug 2008 (PDT)
        • Suggesting the use of rev=fan (as you just did) *is* creating a new microformat using rev, so yes, you are suggesting it. And Google's analysis backed up many years of my (and others') personal anecdotal experience with web developers where >90% did not understand the difference between rel and rev. Tantek 17:53, 6 Aug 2008 (PDT)
          • My point is that as per the HTML 4 definition of rev any time anyone defines a new link type rel=X, the meaning of rev=X becomes defined too. This is unavoidable. We should define new link types in terms of rel rather than rev for clarity, but we can't prevent people from taking advantage of the facilities inherent in (X)HTML to mark up the inverse meaning. (e.g. rev=tag mention, and again, and again) TobyInk 01:17, 7 Aug 2008 (PDT)


For blogrolls at least, what about rel-read / rel-reader? -- Steve Ivy

Steve, "read" is still a verb (and rel-values need to be nouns), and "reader" would still imply that they are a "reader" of yours, rather than vice versa. -- Tantek


What about subscriber instead - also very neutral and more akin to others in the list? --Donohoe 19:55, 5 Aug 2008 (PDT)

"subscriber" is no different from "reader" in this respect, and means the *opposite* of what we are looking for. I.e. a rel="subscriber" link to someone would mean that someone is a subscriber of my content/feed. -- Tantek


Another possibility is perhaps 'favorite', that is, people do link to favorite bands for example, which is similar to saying they are a fan of the band. Thus you could add rel="favorite" to such hyperlinks to indicate that that music band over there is a favorite of yours. Tantek 17:57, 2 Oct 2007 (PDT) based on a question raised by DanBri.

mentors and mentees

Though seemingly rare, I personally have found use for rel="mentor" and inverse rel="mentee" (see Wiktionary definitions: mentor, mentee). I don't have sufficient evidence to even consider proposing adding these to XFN, but I wanted to capture them here as a brainstorm while I look into using them personally and research examples in the wild. I may just use them as POSH myself.

Tantek 02:34, 8 Jul 2007 (PDT)

advisor and advisee

Similarly, I have seen folks reference someone as an advisor, or note that they are advising someone. We could consider rel="advisor" and rel="advisee" to capture and represent these semantics.

Note that the relationship of advising a company or organization would be much better captured by noting "advisor" as a "role" property value in an hCard listing that organization, e.g.:

<span class="vcard">
 <span class="fn">Tantek Çelik</span>
 <span class="org">Citizen Agency</span>
 <span class="role">advisor</span>

Again, I think POSH usage of these terms would make a good experiment to see if there is sufficient use to formalize them.

Tantek 07:45, 29 Dec 2007 (PST)

Influence out and influenced in

Needing to provide more options to describe the flow of influence I've been considering the following relationship terms that fall into two predicate groups, influence out(applied) and influence in(received).

Influence out:

Influence in:

Inline with xfn convention the terms are all nouns and refer to the far side of the link they are used in.

James Tindall 14:23, 31 Aug 2008 (BST)


A possibility that might be added is scholarly definitions. For example rel="mentor"[Student's Teacher] (similar to above), rel="student"[Teacher's Student] (inverse of mentor), rel="classmate"[Student's classmate]. Possible uses in Social Networking sites that involve adding your school, grading your teachers, etc. Teacher <-> Teacher would be specified in with rel="co-worker" or rel="colleague".

Navarr 05:56, 13 Dec 2007 (CST)


see also

xfn-brainstorming was last modified: Wednesday, December 31st, 1969