SUBSTRING extracts part of a STRING based on character position.
The first character has position equal to 1.
If unset the default start position, or index, is at the first character of the string and the default end position, or index, is the last character of the string. The positions may be expressions. If the positions do not lie within the length of the string, or if the end index is less than the start, SUBSTRING will be in an error state, which can be trapped as an EXPAND.
|Value:||Drop down list to select a STRING reference|
|Start Index:||Integer between 1 and length of string. default→1|
|End Index:||Integer between 1 and length of string and must be greater or equal to the start if both set. (default→length of string)|