Nikon D300 User Manual page 687

Figure 10-5. Stored WB values
In effect, you may have up to five White balance values
stored in your camera. One is the current temporary setting,
and the other four are in memory for long-term reuse.
Figure 10-6 shows the steps and menus used to copy the
current White balance value from memory location d-0 to one
of the four storage locations. You'll see a visual
representation of the stored WB values. If there is nothing
stored in d-1–d-4, there will be a blank spot above the
number.
Here's how to save a current WB reading (d-0) to one of
memory locations d-1 to d-4:
1. Use Method 1 to obtain a PRE White balance reading. It
will automatically be placed in memory location d-0.
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