Nikon D300 Complete Manual page 184

3. Use the Direction pad keys to navigate to File
naming and press the > key to select it.
4. Press the > key again to enter the review screen (this
screen shows you what the current file names look
like for both Color Spaces).
5. Press the > key again to enter the entry screen. Enter
the name you wish to use:
a. Use the keys of the Direction pad to navigate to
the letter you wish to enter (white letters on gray
background).
Thom Hogan's Complete Guide to the Nikon D300
V1.02
Page 184