[WindowsCentral.com]

Millions of custom maps from older Halo titles will be accessible in Halo: The Master Chief Collection.

What you need to know

[LIST][*]Over 6.6 million user-generated maps from older versions of Halo have been copied for future access in Halo: The Master Chief Collection.[*]Maps from Halo 3, Halo 4, and Halo: Reach have been copied.[*]The maps are planned to be accessible when Halo: Reach releases on PC.[/LIST]
Over 6.6 million user-generated maps have been copied from Halo 3, Halo 4, and Halo: Reach. These maps will be accessible on Halo: The Master Chief Collection, meaning that users won't lose access to their favorite maps when switching to a new platform.

Full story from the WindowsCentral blog...