When storing numeric fields, using an odd number of digits allows the sign to be included in the storage area without wasting any space.
For example the number -1234567, when packed as 7 digits is stored as follows.
thus taking up only 4 data slots. but when packed as 8 characters it uses 5 data slots
or when 7 digits, non-packed, it will be stored as 8 data slots, including the sign.
Noncompliant Code Example
D NUMFLD S 8P 0
D NUMFLD S 7S 0
D NUMFLD S 7P 0