This notation provides a way to specify certain positions in a string. It is similar to the substring function. The string value of var is evaluated from the jth character to the kth character. Since var( j k ) is evaluated at compile time, it is more efficient than substr(var, pos, len ) and should be used when variable arguments are not needed. The parameters j and k are numeric constants. For more information, see “Field Variables”.

ssn = ssn(1 3) + ssn(5 6) + ssn(8 11); #

Eliminate separators from ssn