Kaynis is correct, in my experience. I do a lot of importing/exporting with OpenERP. the __export__ id's are basically id's that everything else will refer to that record by. I usually create that column on my own and give it a reasonable name in my csv. That way all my future imports can relate to it easier. In the question above, I might name it something like supplier.agrolait just so I can import other related information (such as products) easier by referring to supplier.agrolait, rather than the archaic string it makes for you :) Word of caution, not all external.id's are able to be imported, so test, test, test first.

PS Sorry site was being slow, accidentally messed up my comments a little bit. One other thing worth noting, AFAIK, those external ID's are not created until you export whatever area your working in.

hello guys 

i cant find field (seller_ids/id)  while i am trying to upload products with suppliers (csv) !! could you help me 

You will find a sample file that we used at Open Net for import. Product exemple replace by xls.png The file come with a .png but it's an .xls file Download the file and replace the extension, and you are done.

OK, the file is in french... but you can understand it..