Relation between a Purchase Organisation and Reference PORg

Hi ,

1) Can any one explain me what is the relation between a Purchase Organisation and Reference Purchase Organistion.

2) I have removed the assignment of Purchase organisation 1000 to the Reference POrg 6666 . I want to do the testing in development server after making the above configuation change. Can any one let me know how to do the testing to see that this configuration change is taken place?.

Thanks in advance.