Machine relative offsets

[laguna92651]

I am trying to understand how assembly is translated into machine language. I understand how to get the machine coding formats but I'm not sure how to calculate 'rr' in all cases. For the example example bra is 20 rr or 20 03, I know that the relative offset is 03 to get to the iny instruction. But I'm not sure why the rr = F3 for the dbne instruction, how does that relative offset get me to Again? A quick answer would be appreciated, I have a test tomorrow.

Solution to sample problem:

org $600   
                      ldy  #Array        ;CD B6 15
                      ldaa  #N            ;86 07
                      clr      7,y           ;69 47
Again             brclr   0,y %11110000, Not_gtr  ;0F 40 F0 02
                      bra    Update     ;20 03
Not_gtr          inc     Count       ;72 B6 1C
Update          iny                      ;02
                      dbne  a,Again    ;04 30 F3
                      swi                     ;             
Array             fdb   8,7,2                           
N                   equ   7
Count            rmb   1