The EndNote documentation page “Creating a Tagged EndNote Import File” reads:
“The default reference types are listed below. If you have modified a reference type, your EndNote data files should use the new name instead.”
I have modified “Unused 1” to use a custom type named “NewName.” The import file starts with “%0 NewName.” When importing the file, the resulting records are assigned a reference type of “Book.”
Test System: Thomson Reuters EndNote X5.0.1 (Bld 5774); Microsoft Windows 7 Professional Service Pack 1 (64-bit)