Dear Chris, 

Thanks a lot for your answer. This is not exactly what I needed (my english is not really great i assume). 

This is an accounting problem. Actually we have a supplier for our accounting and i need to export them all the informations from the accounting journal. And i need to identify each supplier with an accounting third party name. 
For example a supplier name Norronac all the invoices are registered in accounting code 601100. But there is also other invoice from other supplier which are registered in this accounting code. I need to identify clearly Norronac with a third party account (like FNORRO) this way I can have like an account journal only for Norronac. 

usually we can set it up in directly in the supplier contact (but i can't find where). 

Thanks for help. 
Regards, 

Claire  

Hi Claire,

Here's another suggestion:

1. Set a reference for each supplier

2. Add the field when you download to Excel 

3.  If you have Studio, you can add it as a Related Field

I always rename the field to make it clearer, but this is optional

Now it is shown:

[original answer for reference in case it helps anyone else]

If you create portal users and they can access their own orders / invoices / tasks:

As standard this works for customers, not vendors.