Data can be imported into system attributes System fields, while a part of Microsoft Dynamics CRM Online by default, cannot be customized or added to a solution. System fields do not display in the Customization area. and custom attributes Fields created by a developer or System Customizer in Microsoft Dynamics CRM Online. They are created in the customization area and can be included in a solution. Custom fields might be further customizable, depending on restrictions placed on them when created. in most record types, and can also be imported into custom record types Record types that are not included in Microsoft Dynamics CRM Online by default. You can create custom record types by using the customization tools. Also called custom entities..
For a complete list of record types you can import into, on the second page of the Import Data Wizard, view the values in the Record type list.