Adding a UCA Collation to a Unicode Character Set Logical Position Unicode 4.0.0 Code Point Unicode 5.2.0 Code Point <last_secondary_ignorable/ > U+FE73 U+FE73 <first_tertiary_ignorable/ > U+0000 U+0000 <last_tertiary_ignorable/ > U+FE73 U+FE73 <first_trailing/> U+0000 U+0000 <last_trailing/> U+0000 U+0000 <first_variable/> U+0009 U+0009 <last_variable/> U+2183 U+1D371 •The  <collation>  element permits a  shift-after-method  attribute that affects character weight calculation for shift rules. The attribute has these permitted values: • simple : Calculate character weights as for reset rules that do not have a  before  attribute. This is the default if the attribute is not given. • expand : Use expansions for shifts after reset rules. <reset>0</reset> <pc>abcdefghijklmnopqrstuvwxyz</pc> ’a’ has weight 0E29+1 ’b’ has weight 0E29+2 ’c’ has weight 0E29+3 ... ’a’ has weight [0E29][233D+1] ’b’ has weight [0E29][233D+2] ’c’ has weight [0E29][233D+3] ... <collation id=" nnn " name="utf8_ xxx _ci" version="5.2.0"> ... 2003 MySQL-Specific LDML Extensions Suppose that  ’0’  and  ’1’  have weights of  0E29  and  0E2A  and we want to put all basic Latin letters between  ’0’  and  ’1’ : For simple shift mode, weights are calculated as follows: However, there are not enough vacant positions to put 26 characters between  ’0’  and  ’1’ . The result is that digits and letters are intermixed. To solve this, use  shift-after-method="expand" . Then weights are calculated like this: 233D  is the UCA 4.0.0 weight for character  0xA48C , which is the last nonignorable character (a sort of the greatest character in the collation, excluding CJK). UCA 5.2.0 is similar but uses  3ACA , for character 0x1342E . An extension to LDML rules permits the  <collation>  element to include an optional  version  attribute in  <collation>  tags to indicate the UCA version on which the collation is based. If the  version  attribute is omitted, its default value is  4.0.0 . For example, this specification indicates a collation that is based on UCA 5.2.0: