The purpose of the migration tool provided with the IUCLID 5 application is to make it as easy as possible to reuse data entered in IUCLID 4 in the new IUCLID 5 version. The tool is designed in such a way that the IUCLID 4 data contained in export files are transformed to the new IUCLID 5 format without any user intervention. The transformed data can then be imported - completely or partially - into any IUCLID 5 instance. This import can also be done in a "batch mode", i.e. without any user intervention.

Care has been taken to map the information present in IUCLID 4 to the corresponding fields in IUCLID 5. There are many thousand rules specifying the exact mapping to preserve every possible field and make the information usable also in the new IUCLID 5 version 5. However due to the complete overhaul of the data structure in IUCLID 5, not all source fields have direct target fields. This is no problem in cases where the IUCLID 4 information concerned is of minor or no relevance and also not addressed in IUCLID 5 (e.g. a summary on the Company information). However, in cases where information cannot be migrated automatically, user intervention in terms of cleansing the IUCLID 4 data before migration or post-processing migrated data may be required, as will be discussed in more detail below. This is most often the case when information stored in free text fields of IUCLID 4 is split up to several structured fields in IUCLID 5.

It should be recognised that any freetext, regardless of whether it is structured or not, can only be migrated "as is" to the corresponding rich text fields in IUCLID 5. For example, a IUCLID 4 freetext of type ME (Method) or TC (Test conditions) is transferred to IUCLID 5 field Any other information on materials and methods incl. tables. This pertains also to the so-called sample freetexts provided with the IUCLID 4 Guidance Document (2000). Although these sample freetexts were used by a number of IUCLID 4 users for OECD SIDS and partly also for BPD-related datasets, they were often modified. Hence, no standardised structure is available for these elements and no distinct target fields could be defined for the different pieces of information contained in these structured freetexts.

Nevertheless all information present in IUCLID 4 will still be preserved in the migration process. In cases where the information cannot be migrated into any field in IUCLID 5, an entry in the migration report will be created where the exact place of the problem is specified and the non-migrated data is deposited. After the import of the migrated dataset(s), the migration report is attached to the newly created IUCLID 5 Substance dataset in the form of a PDF document. It is intended to assist the user in the decision on what data need to be checked and/or manually moved to a specific target field.