What is registerLinkHandler for?

by Mike Churchward.  

Hi -

While working on a new plugin for mobile, I can see that the examples (certificate, in particular) register a link handler along with a content handler, using a statement like:

$mmContentLinksDelegateProvider.registerLinkHandler('mmaModCertificate', '$mmaModCertificateHandlers.linksHandler');

What is this handler for? Where is it actually used?

mike