Sony HDS-7100 User Manual page 280

Enabling or disabling the FREZE button – F4 (FREEZE BUTTON)
To disable the FREZE button on the control panel, so that pressing
it has no effect, press F4 (FREEZE BUTTON) to select "Disable".
To restore the effect of the FREZE button, press F4 (FREEZE
BUTTON) to select "Enable".
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Chapter 10 Setup Operations