Character Definition Arrays 4. Reconfigure, recompile, and test. 10.13.1 Character Definition Arrays 1990 Each  <collation>  array indicates how characters should be ordered for comparison and sorting purposes. MySQL sorts characters based on the values of this information. In some cases, this is the same as the  <upper>  array, which means that sorting is case-insensitive. For more complicated sorting rules (for complex character sets), see the discussion of string collating in Section 10.13.2, “String Collating Support for Complex Character Sets” . lower[’A’] should contain ’a’ upper[’a’] should contain ’A’ The  <lower>  and  <upper>  arrays hold the lowercase and uppercase characters corresponding to each member of the character set. For example: The bitmask values in  m_ctype.h  are octal values, but the elements of the  <ctype>  array in  MYSET .xml should be written as hexadecimal values. ctype[’A’+1] = _MY_U | _MY_X = 01 | 0200 = 0201 The  <ctype>  value for a given character should be the union of the applicable bitmask values that describe the character. For example,  ’A’  is an uppercase character ( _MY_U ) as well as a hexadecimal digit ( _MY_X ), so its  ctype  value should be defined like this: #define _MY_U 01 /* Upper case */ #define _MY_L 02 /* Lower case */ #define _MY_NMR 04 /* Numeral (digit) */ #define _MY_SPC 010 /* Spacing character */ #define _MY_PNT 020 /* Punctuation */ #define _MY_CTR 040 /* Control character */ #define _MY_B 0100 /* Blank */ #define _MY_X 0200 /* heXadecimal digit */ <ctype>  array elements are bit values. Each element describes the attributes of a single character in the character set. Each attribute is associated with a bitmask, as defined in  include/m_ctype.h : Most of the arrays are indexed by character value and have 256 elements. The  <ctype>  array is indexed by character value + 1 and has 257 elements. This is a legacy convention for handling  EOF . For a complex character set as implemented in a  ctype- MYSET .c  file in the  strings  directory, there are corresponding arrays:  ctype_ MYSET [] ,  to_lower_ MYSET [] , and so forth. Not every complex character set has all of the arrays. See also the existing  ctype-*.c  files for examples. See the CHARSET_INFO.txt  file in the  strings  directory for additional information. • <collation>  elements indicate character ordering for comparison and sorting, one element per collation. Binary collations need no  <map>  element because the character codes themselves provide the ordering. • <unicode>  maps 8-bit character values to Unicode values. • <lower>  and  <upper>  list the lowercase and uppercase characters. • <ctype>  defines attributes for each character. Each simple character set has a configuration file located in the  sql/share/charsets  directory. For a character set named  MYSYS , the file is named  MYSET .xml . It uses  <map>  array elements to list character set properties.  <map>  elements appear within these elements: