From Fedora Project Wiki

Fedora Legacy - Community Maintenance Project

The Fedora Legacy Project was a community-supported open source project to extend the lifecycle of select "maintenance mode" Red Hat Linux and Fedora Core distributions. The current model for supporting maintenance distributions has been re-examined. Fedora Legacy was unable to extend support to older Fedora Core releases as it had planned. As of now/ Fedora Core 4 and earlier distributions are no longer being maintained. Fedora Core 5 will no longer be maintained 30 days after the Fedora 7 release.

"Legacy Repo was included in Fedora Core 6","Fedora Core 6 shipped with a software repository configuration for Fedora Legacy. This repository was not enabled by default in the Fedora Core 6 release."