| Bar Codes / Bar Code type details | |
Details on the data-matrix bar code type.
A Data matrix bar code can be used to encode text and binary data of variable length. It is possible to encode up to 1558 code words. Text, binary data and numeric data are compressed into code words so that the limits for these types are:
The limits for mixed text are lower, as control characters are inserted to switch between the different compression modes.
Data matrix symbols exist in several flavors with varying methods and degrees of error correction. Of the possible options ECC 000, ECC 050, ECC 080, ECC 100, ECC 140 and ECC 200 this implementation supports only ECC 200 using Reed Solomon error correction.
Special control characters like FNC1, ECI and "structured append" are currently not available.
The conversion of the data specified in this attribute (codeValue) to the internal representation is done by an algorithm that minimizes space. Byte values that cannot be represented in an XML document (for example all characters lower than 0x20 except 0x9, 0xa and 0xd) can be represented by a backslash ('\') character followed by a 3 digit octal literal. The backslash character itself can be escaped by a sequence of two backslash characters.
The current implementation can encode any character that exists in the code page ISO-8859-1 (Latin 1). Any attempt to encode other characters will fail. Future versions will insert ECI control characters to switch to other code pages if the character is available there.