FANUC 18i Offset

[AKamil]

Hi,
I am writing a cnc program to Anderson's Exxact machine which works with FANUC 18i controller.
I am using a sample cnc program which has the following lines:
%
O0470 ( NESTING )
(RECHTER TISCH)
M06
M98 P9998
G10 G90 L2 P0 X0 Y-1600.0 V-1600.0
G91 G28 Z0.0 A0.0
M23 S4000 ( VERTIKAL BOHRER)
G90
G10 G90 L2 P2 X-280.6 Y-165.7 V-165.7 Z34.0
G55
G17
M21 G1 G43 H72 Z80.0 F6000
M89 T2
...
T108 ( FREZ DIAMENDOWY )
M13 S18000
G90
G10 G90 L2 P2 X-812.9 Y25.5 V25.5 Z34.0
G55
G17
M11 G1 G43 H20 Z40.0 F10000

I understand that G10 means offset setting for G55 work coordinate system. However, I don't know where to take the X, Y and Z values from and what is the implications of the offset setting on the cutting process.