qCRC

                    Checksum
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A simple sum of all bytes (or words) in a block
of data, taken modulo 256 (or 65536).  Used to
verify data integrity.

          (CRC) Cyclic Redundancy Code
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Like a checksum, but using a complicated formula
that avoids offsetting errors.

      (ECC) Error Checking and Correction
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Like a CRC, but containing more information.
With an ECC, it is possible to detect all errors
and to correct all single-bit and some multiple-
bit errors.