Nikon D6 Reference Manual page 807

Storage Folder
Choose the folder in which subsequent pictures will be stored.
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Renaming Folders
The default folder name, which appears after the folder number,
is "NC_D6". To change the name assigned to new folders, select
[Rename].
•
Existing folders cannot be renamed.
•
If desired, the default name can be restored for subsequent
folders by pressing and holding the O ( Q ) button while the
keyboard is displayed.
G button U C photo shooting menu
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C The Photo Shooting Menu: Shooting Options
Folder
1
Folder number
2
Folder name
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