SIGNED returns a signed FIXED BINARY value of x, with
a precision specified by p and q.
>>-SIGNED(x-+-----------+-)------------------------------------>< '-,p-+----+-' '-,q-'
- x
- Expression.
- p
- Restricted expression that specifies the number of digits to be maintained throughout the operation.
- q
- Restricted expression that specifies the scaling factor of the result. For a fixed-point result, if p is given and q is omitted, a scaling factor of zero is the default.