Provider-driven identity adoption
Refers to adoption of YADIS-enabled identities that is driven by the provider, i.e. the organization that runs the web server that serves Yadis identities.
An example for this would be BigISP. If BigISP decided to serve the X-Yadis-Location header with all HTTP responses to requests to their customer's home pages, they would "flip the switch" on for all of them, without the customers having to do anything.
Compare to user-driven identity adoption.