substring

The substring function returns a part of a given string.

substring(string, start)
substring(string, start, length)

string: The string to evaluate.
start: The position within string the substring begins
length Optional: The length of the substring. If omitted, the returned string will contain every character from the start position to the end of string.

A string.

As in other XPath functions, the position is not zero-based. The first character in the string has a position of 1, not 0.

Supported.