Sony MSAC-USM1 Operating Instructions Manual page 27

Write-protecting data
A "Memory Stick" is equipped with an erasure prevention switch to
ensure that important data is not deleted by mistake. (Some of "Memory
Stick" ("Memory Stick Duo") are not equipped with an erasure prevention
switch. If you use a "Memory Stick" ("Memory Stick Duo") unequipped
with the erasure prevention switch, be careful not to write data or delete
data by mistake.) Sliding this switch to the left or right enables or prevents
writing of data to the "Memory Stick."
• Write enable
Data can be written.
• Write protect
When the switch is moved to the right, the condition becomes the one in
which data cannot be written to the "Memory Stick." Data can be read
out but writing is prevented.
Underside of "Memory Stick"
Data read/write speed
The data read/write speed differs with the "Memory Stick" and product
combination that you are using.
Write enable
LOCK
LOCK
Write protect
LOCK
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