SUBSTR(arg1, arg2, arg3)

Extract a sub-section of string arg1 of length arg3 starting at character arg2. If arg2 is positive then the start position is arg2 characters from the left, If arg2 is negative then the start position is arg2 characters from the right. The length (arg3) is optional and if omited is taken to be to the end of the string.

e.g.

	SUBSTR("the quick brown fox", 4, 5)

	will return the string "quick"

	SUBSTR("the quick brown fox", -3, 5)

	will return the string "fox"

	SUBSTR("the quick brown fox", 4, 5)

	will return the string "quick brown fox"

	SUBSTR("the quick brown fox", -7)

	will return the string "own fox"

NOTE:

SUBSTR() will return the empty string ""
SUBSTR(arg) will return the string arg