## Substring

This function is used to extract a substring of a field and save it to a Variable field.

The location index is zero based. ie. the first character in a field is at index 0. A location field which evaluates to be less than zero is treated as relative from the end of the field.

A length field which evaluates to be a negative number is interpreted as to the end of the field.

All supplied text fields may contain any of the escape sequences described in Escape Sequences.

Think of the location and length as defining a range of characters. The function returns the characters from the field that are within the evaluated range.

examples with a field of "abcde"

> - location=1, length=2 --> "bc"
> - location=2, length=-1 --> "cde"
> - location=-3, length=2 of --> "cd"
> - location=6, length=1 of --> ""
> - location=-7, length=3 of --> "a"