Have they done this?
Impact analysis on every data item
Data structures: field, record, table, outputs, interchange formats
Program code, maps, UI controls, mail merge, external report file specifications, query strings, configuration files, and DLLs.
How they know all and only the data points that need converting
Transaction amounts and parameters e.g. credit limits
Numerics that should not be converted like quantities and rates
Amounts in non-numeric fields like memos?
Data Quality checks before conversion to clean up the data (consistency, completeness, "special values", field expansion)
Data integrity checks afterwards to verify
These are detailed questions if you are enquiring into the quality standards of the software producer.Most users will prefer to rely on certification standards.
The BASDA (www.basda.org) standard tests for conversion, inverse rates, and triangulation, and have now introduced a second level of certification for the changeover of account balances.
The IBM checklist (http://www.ibm.com/espace-pme/fr) is a form of self-certification. It provides a detailed and well-thought-out checklist based on FEE (www.euro.fee.be) which is provided to the suppliers but the web site only displays the answers to the broader questions. The results are expressed as answers to questions on how the software works rather than in the terms a non-technical manager would understand on how that affects their accounting.
The German national standard "EURO/JAHR 2000" from DIN (Deutsches Institut fuer Normung) explicitly covers a general ledger over a three-year transition scenario and gives tests and results. The certification agency is GPS (Gesellschaft zur Prüfung von Software mbH)
Aquitaine Valley, the agency which certifies compliance with the AFNOR "NF Euro compatibilité" standard in France does not release details of its tests. They state that they have defined test processes covering inspection, sampling, and application-specific functionality, and some features that add some assurance of good process management by the software company .