I can explain.
15,2 Packed Decimal
15,2 means 15 decimal digits, 2 to the right of the decimal point.
Packet Decimal means that you store your decimal digits in 4-bits each (nibbles). 15 digits would require 8 bytes or 16 nibbles. That's Packed Decimal, a legacy numeric data type used to save storage space back in the days when megabyte drives cost megabucks.
HTH
Gotcha !!! :>)