$substr (start-char, num-chars) function

Return a string from the target message starting at start-char position and continuing for num-chars character count. The resulting string can contain any number of characters and characters of any type (including spaces). This function is particularly good at parsing session identifiers or other arbitrary character data based on a start character in the message.

Target String	Parse Expression	Return Value
AA BB CC DD EE	$substr(5, 6)	B CC D
123456789012345	$substr(3, 2)	34
123456789	$substr(3, 99)	3456789 Warning Note The number of characters exceeds the length of the string, and all characters are returned.
ABCDE	$substr(10, 1)	No match. The start char first argument is longer than the target string.