OKB9 SETTINGS

Hi pls explain me okb9 settings when it is required

because we r gettings issues regarding while slaes stock transfer one plant to another plant

Gl a/c requires co object?

in this case we do normally we go to KA02 and we give the costcentre for the plant

but pls explain when we have to use okb9? and purpose where it links?

urgent

regards

arun