Caché MultiValue Basic Reference ABS Search:

Returns the absolute value of a number.
Synopsis
ABS(number)
Arguments
 number An expression that resolves to a number or a numeric string.
Description
The absolute value of a number is its unsigned magnitude. For example, ABS(-1) and ABS(1) both return 1. ABS returns a number in canonical form; it removes plus and minus signs and leading and trailing zeros from number. A string is parsed as a number until a non-numeric character is encountered. Thus “7dwarves” is parsed as 7. If number is the empty string ("") or a non-numeric value, ABS returns 0 (zero).
The ABS function gives the absolute value of a number: all numbers become positive. The NEG function inverts the sign of a number: negative numbers become positive and positive numbers become negative.
Examples
The following example uses the ABS function to compute the absolute value of a number:
PRINT ABS(0050.300);  ! Returns 50.3
PRINT ABS(-50.3);     ! Returns 50.3
PRINT ABS(+50.3);     ! Returns 50.3
PRINT ABS(0);         ! Returns 0
PRINT ABS(-0);        ! Returns 0