Make the following changes in your source .csv files or your data map before importing data:
Change values in the ID fields for any record type other than the 18 record types in the sample data map.
When an ID field is blank, Salesforce.com substitutes a value of 000000000000000AAA for the field when exporting data to a file by using the full-data export feature.
For 18 record types that are included in the data map for Saleforce.com, the data map uses transformation A type of mapping used to modify data before migrating it. Transformations include concatenation, split, replace, substring, assignment, and date modifications. to map the values of these ID fields. You do not need to do anything.
For a record type that is not included in the data map, either edit the source file to replace each 000000000000000AAA with an empty field, or use a Replace transformation as part of the import process.