The incoming URL determines which responder gets activated. There are many different types of responders (and more every iteration!)
^TestNameResponder
^TestRssResponder
^SuiteSearchResponder
^SuiteRunResponder
^SuiteEditResponder
^SuiteRenameResponder
^SuiteMoveResponder
^SuiteTestResponders
^SuiteVersionResponder
.FrontPage .RecentChanges .FitNesse.SuiteAcceptanceTests
^TestNameResponder
^TestRssResponder
^SuiteSearchResponder
^SuiteRunResponder
^SuiteEditResponder
^SuiteRenameResponder
^SuiteMoveResponder
^SuiteTestResponders
^SuiteVersionResponder
.FrontPage .RecentChanges .FitNesse.SuiteAcceptanceTests