
The function returns the strg with occurrences of
characters in the search_list
replaced by the character at the corresponding position in the replace_list.
If there is a character in the search_list with no character at a
corresponding position in the replace_list
(because the replace_list is longer than the replace_list),
then occurrences of that character in strg string are removed.

If a character occurs more than once in the search_list,
then the first occurrence determines the replacement character.
If the replace_list is longer than the search_list,
then excess characters are ignored.

Two popular use cases for this function are case conversion and sorting with collation.
For "to-upper" case conversion,
the search_list consists of all lowercase characters of some language and
the replace_list consists of all uppercase characters of that language.
For "to-lower" case conversion, uppercase chars are in the search_list
and lowercase are in the replace_list.
For sorting with collation, the function must be used in "select" string expression
attribute of <xsl:sort> element; the search_list consists of all
characters reordered by collation and the replace_list consists of
corresponding characters from "collation string".
