Standbys differ from documentary credits in several important respects.
As their name implies, documentary credits pay against documents that prove certain events took place. For instance, a shipment can be evidenced by a transport document, origin of goods by a certificate of origin, insurance by an insurance certificate, etc. Since it is impossible to prove a negative, standbys cannot require conclusive documentary evidence. This makes standbys susceptible to misuse by beneficiaries who are willing to lie. Another difference is that documentary credits are intended to be used.