Different display Format

[Pavan Yadav]

Hi,
Can anyone let me know in detail about the display format tricks as:

define variable i as INTEGER INITIAL 9-.
DEFINE VARIABLE j AS INTEGER INITIAL 8-.

Display i format '-zzzzzzz9.99'.
Display j format '-99999.99'.

I dn't have the explanation for this i.e why it's behaving like this... Is Z behaves as character over here?

Thnks in advance