System messages related to Invoice Verification

Hi Experts,

Could you please explain when system will issue below four messages during MIRO (Invoice verification) transaction.

M8 286 Different invoicing party & planned in purchase order & E E

M8 287 Different invoicing party & planned for del. costs item in PO & E E

M8 288 Different invoicing party & planned in purchase order & E E

M8 289 Different invoicing party & planned for del. costs item in PO & E E

Generally whenever business users are creating invoice with the vendor other than the PO vendor, system will issue these messages.

But for above mentioned 4 messages, description is almost same. That's why I am confusing. In my case message nos 286 & 288 are very important.

I am getting messages no 286 during creation of Invoice with different vendor other than PO vendor.

So for the remaining 3 messages, I am not able to test business processes.

Could you please explain when system will issue these messages (other than 286) during MIRO.

Thanks in advance

Regards

KRK