Sony PCV-LX920 - Manual (Page 45)

To protect data on Memory Stick media from accidental changes
Memory Stick media contains a write-protect tab. The write-protect tab prevents accidental changes to information recorded
on your Memory Stick media. When you slide the write-protect tab to the LOCK position, your Memory Stick media is
write-protected. This means that you cannot delete, copy, or save information on the media. When you slide the tab to the
un-LOCK position, you can write to or modify your Memory Stick media's contents.
Locking the Memory Stick Media
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