“Single Window is defined as a facility that allows parties involved in trade and transport to lodge standardized information and documents with a single entry point to fulfil all import, export, and transit-related regulatory requirements”
UN/CEFACT RECOMMENDATION No. 33
The development of the Single Window is typically a major undertaking, involving the creation of inter-linkages and information sharing between Customs and other government agencies responsible for trade, as well as the trading community. It is therefore usually implemented in a phased approach.
Basically, successful implementation of the Single Window focuses more on simplifying and managing changes, rather than on technical solutions.