breadcrumbs-formats

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This page is a collection of research regarding previous breadcrumbs formats towards the development of a breadcrumbs vocabulary and microformat per the process.

ARIA breadcrumbs

Accessible Breadcrumbs Markup format uses ARIA's navigation role and aria-label (role="navigation" aria-label="breadcrumbs"). E.g. HTML5 example:

<nav role="navigation" aria-label="breadcrumbs">
  <a href="/">Home</a>
  <span aria-hidden="true"></span>
  <a href="/library">Library</a>
  <span aria-hidden="true"></span>
  <a href="">Data</a>
</nav>

Bing breadcrumbs

Bing breadcrumbs format: http://www.bing.com/webmaster/help/markup-breadcrumbs-72419f3f

Google rich snippet breadcrumbs

Google Rich Snippets have a 'breadcrumbs' construct, as does its schema.org successor

schemaorg WebPage

schema.org WebPage specifies breadcrumb as 'Text A set of links that can help a user understand and navigate a website hierarchy.' Which is an odd way to specify links.

add more formats

copy paste this subsection to add more formats.

sitemap formats

This might be worth moving to sitemap-formats and just linking to as "related", as sitemaps have overlap with, are similar to (and can inform) breadcrumbs, but they're certainly not the same thing.

This strays more into sitemaps and topic description; related themes...

Late-90s Mozilla/Netscape browser had built-in understanding of a sitemaps format expressed in RDF. Technical details are likely buried in Mozilla CVS; some press releases still survive. The vocabulary encoded a sitemap as a graph structure, using a 'child' property to represent hierarchy, as in other areas of Mozilla (e.g. see Mozilla docs, mail/news).
Mozilla's RDF sitemaps were preceded by Meta Content Format (MCF) sitemaps (Netscape took MCF from Apple ~1997). MCF sitemaps described a site hierarchy using a network of linked text files that summarised the site structure. MCF was an ancestor of both RSS and RDF.
ILRT / University of Bristol had a server-based implementation of the same format (now code-rotted), and experiments with alternatives that instead used more HTML concepts: see 1999 draft spec
more recent work around RDF has focussed on describing hierarchies of topics using the SKOS vocabulary; this has gained significant traction in the library community, and many thesauri are shared using SKOS. However it is not widely used to annotate in-page topic hierarchies. See CKAN list of datasets using SKOS.