Is it possible to make couple of shipments under the same proforma invoice?

Proforma invoice used as a simplified form of a sales contract in today's international business transactions. 

Many companies do not waste their times to write down a detailed sales contract, but instead they send a single page proforma invoice to their buyers.

In some occasions, a proforma invoice may cover an order which will be shipped not in once but under several shipments. 

This action is defined as partial shipment.

Partial shipment should be allowed by the sales contract or a proforma invoice under normal conditions. 

It is worth mentioning that, letter of credit rules also allow partial shipments as well.

But in some special situations, importers may prohibit partial shipments. In such a case, partial shipment should not be allowed under the sales contract or the letter of credit conditions.