OK, so this is from panasonic november2004, in how to treat your plasma back then - Im assuming this has come on since then for panels such as my ph9:
Plasma Break-In
Like a fine new automobile, the performance of a plasma TV can be
optimized by allowing a break-in period. By properly following these simple
break-in instructions, you should be rewarded with long-term enjoyment of
your plasma TV.
Plasma phosphors are most susceptible to image retention in the first
hundred hours of use. The panel becomes considerably less sensitive to
burn-in after this period.
Very often, televisions, including plasma, are shipped from the factory with
the contrast control at a high setting to provide a bright picture under typical
dealer showroom lighting conditions. In your home, the room light levels are
usually one half or less than that in retail showrooms. The contrast control
may need to be lowered in your home for comfortable contrast levels that do
not induce eye strain.
When the plasma is initially installed, videophiles say it is best to do the
following:
y Make sure the display is in a viewing mode (aspect ratio) that completely
fills the screen (there are often three or more settings from which to
choose). The panel is shipped in this condition, in what is called the
“Just” mode.
y Turn down the picture control (contrast) to 50% or less.
y Briefly engage the 4:3 mode to confirm the side bars are set to mid-gray
(there is usually an adjustment in the Set Up menu that takes the
sidebars from black to gray) to minimize the chance of burn-in.
y Return the set to a “full screen” (Just, Zoom, Full) position during the
first hundred hours of use.
y During the first hundred hours of use it is best not to view the same
channel for extended periods. This should prevent channel logos and
other fixed images found on some channels from being retained.
y Avoid any static images (video games, computer images, DVD title
screens, etc.) during the hundred-hour break-in.
After the hundred-hour break-in period, during the next nine-hundred hours
eek: ):
y Continue to retain the picture setting at 50% or less.
y Limit the use of 4:3 aspect ratio mode (traditional picture size that does
not fill the entire screen) to 15% of viewing time.
y Limit the use of static images (computer, video games, etc.) to less than
10% of viewing time.
After one-thousand viewing hours, panels are much less likely to experience
image burn-in.