It will probably once again become clear to all those involved that the interplay of different systems can be different in real life than in a test scenario, however realistic it may be.
The Year 2000 changeover has a different type of complexity than the introduction of the euro, since there is an interaction between different EDP applications, system components and external software components, as well as processor-driven systems. Substituting the euro for the DM will involve the organisation of workflows and operating procedures; in computer-related terms, that means new software must be installed.