SATO CL4NX Programming Reference Manual page 460

dlk:
Dynamic lock
Note that once locking the target with 1, you cannot set 0 to clear it.
Parameters for Block Lock (omissible)
If the capacity of user memory exceeds 12 blocks, control can be
applied to specified blocks from the 13th block onwards.
Please set a fixed, 6-digit hexadecimal.
Please set a 4-digit hexadecimal for NTAG203 and MIFARE Ultralight-C.
Set an 8-digit hexadecimal for my-d move NFC.
There are two types of bit images, locking multiple blocks (L) and block-
locking multiple blocks (BL). It depends on the product as to which
block will be allocated for each bit (See the following bit image chart for
specifying dynamic block lock).
The specified block will be write protected when you specify 1 in place
of L (will be made read-only).
The target range of blocks will be fixed with the current restrictions when
you specify 1 in place of BL. The block without L-lock cannot be made
read-only, so it will constantly be read-write.
At the same time, you specify the L and BL for the same block, the
target block is read-only reduction.
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