Bink.nu just release a great White Paper on BCDEdit :
On Microsoft Windows Vista and later versions, the boot configuration data (BCD) store, contains the boot configuration parameters and controls the computer's boot environment. BCDEdit is a Windows Vista command-line tool that can be used to add, delete, edit, and modify data in a BCD store. The paper is a reference for BCDEdit commands, data types, and well-known identifiers.
Source : bink.nu