[For more current case annotated texts by this author, see Bernstein & Lookofsky, Understanding the CISG in Europe, 2d ed. (2003) and Lookofsky, Understanding the CISG in the USA, 2d ed. (2004).]
258. Under the general Convention rule, the seller is entitled to avoid (tenninate) only by reason of the buyer's fundamental breach. However, in cases where the buyer does not pay or take delivery, the seller may also avoid if the buyer does not perform within an additional period of time fixed by the seller in accordance with paragraph (1) of Article 63. This rule provides:
Once the buyer is late in performing, the seller may have reason to doubt whether the buyer will perform before the breach becomes truly serious, thus entailing a substantial detriment which would entitle the seller to avoid; indeed, the seller may have reason to doubt how the Convention requirement of fundamental breach will be applied in a given case. For this reason, the CISG gives the seller the right to fix an additional period of time, after which the seller may avoid without having to consider whether the total delay has reached 'fundamental' proportions.
Once a Nachfrist notice is sent, the seller must await the buyer's reaction. During the period fixed, seller may not resort to any remedy he might otherwise have by virtue of the breach.