XML in a Nutshell, 3rd Edition

Name

substring( )

Synopsis

                     string substring(string s, number index, number length)
string substring(string s, number index)

The substring( ) function returns the substring of s starting at index and continuing for length characters. The first character in the string is at position 1 (not 0, as in Java and JavaScript). For example, substring('Charming cat', 1, 5) returns "Charm“. If length is omitted, then the substring to the end of the string is returned. For example, substring('Charming cat', 10) returns "cat“. As usual, any type of object may be passed to this function in place of the normal argument, in which case it is automatically converted to a string before extracting the substring.