The sort key is a nineteen-digit number. For numbers within range the first four digits are determined by the number's sign and order of magnitude and the next fifteen digits are determined by the number's sign and significand.

• For numbers between 10−308 and 10308 the first four digits are calculated by adding 7000 to the order of magnitude and the next fifteen digits are calculated by multiplying the significand by 1014.
• For numbers between −10−308 and −10308 the first four digits are calculated by subtracting the order of magnitude from 2999 and the next fifteen digits are calculated by subtracting the significand from 10 multiplying the difference by 1014.
• The sort key for 0 is 5000000000000000000.

• Numbers larger than 10308 are assigned the sort key 9000000000000000000.
• Numbers smaller than −10308 are assigned the sort key 1000000000000000000.
• Numbers between 10−308 and 0 or between 0 and −10−308 are assigned the sort key 5000000000000000000.