Lexmark T656 Technical Reference Manual page 54

number of rows used to build the symbol will be determined by the "codewords:columns" ratio. For
example, if columns is set to 10, rows is set to 0, and the symbol requires 80 codewords, the symbol
will be built with 8 rows (80 codewords / 10 columns).
Columns: (Default = 00x)
This can be used to manually set the number of symbol columns. Both columns and rows must be
00x if using aspect ratio. Valid non-zero values are 01x to 1Ex (1 to 30 decimal). A value of 30 will be
used in place of any specified non-zero value greater than 30. If rows is a valid non-zero value, and
columns is zero, the number of columns used to build the symbol will be determined by the
"codewords:rows" ratio. For example, if rows is set to 15, columns is set to 0, and the symbol
requires 90 codewords, the symbol will be built with 6 columns (90 codewords / 15 rows).
Note: When manually setting the number of symbol rows and columns, rows and
columns must be no more than 928. A symbol size of rows = 90, columns = 16 will
be used in place of any specified values for rows and columns that exceed this
limit. Any time the data given for a symbol requires a larger symbol than that
specified by a manual setting of rows and columns, the rows and columns setting
will be ignored, and the default aspect ratio of 1:2 will be used.
Aspect ratio Y: (Default = 01x)
Aspect ratio can be used as an alternate way of designating rows and columns. To use aspect ratio,
rows and columns must both be zero, and aspect ratio Y and aspect ratio X must both be non-zero.
An aspect ratio of 1:2 will be used if either aspect ratio Y or aspect ratio X is set to zero.
Aspect ratio X: (Default = 02x)
Aspect ratio can be used as an alternate way of designating rows and columns. To use aspect ratio,
rows and columns must both be zero, and aspect ratio Y and aspect ratio X must both be non-zero.
An aspect ratio of 1:2 will be used if either aspect ratio Y or aspect ratio X is set to zero.
ECC by percentage, bytes 1 and 2: (Default = 0000x)
These two bytes designate error correction levels by percentage. Valid percentage values range from
0% to 400%. Any values outside this range are ignored. A valid non-zero value will override ECC by
predetermined value. A zero value will cause the predetermined ECC value to be used.
If a valid non-zero percentage is specified, the ECC level will be computed by selecting one of the
predetermined ECC levels (0-8). The ECC level selected will be the one that best matches the
number generated by multiplying the specified percentage by the number of data code words in the
symbol.
For example, if there are 20 data code words in a symbol, and ECC percentage is specified at 100%
(0064x), then the predetermined ECC level selected will be the one closest to 20, or ECC level 3 (16
error code words).
For the same 20 data code words, and an ECC percentage specified at 35% (0023x), ECC level 2 (8
error code words) will be selected, because it is closest to 20 x 0.35, or 7.
Two-dimensional bar codes
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