If your source file contains columns that don't map to existing Microsoft Dynamics CRM Online fields, you can use the Import Data Wizard to create a custom field in any record type as part of the import process.
New fields are created in Microsoft Dynamics CRM Online, but are not added to the form for the record type or to any views for the record type. After the import is complete, you need to go to the Customization area of Microsoft Dynamics CRM Online to complete these tasks.
If you use the Import Data Wizard to create a new field of bit Attribute type with two valid string values that are mapped within Microsoft Dynamics CRM Online to be stored as 1 or 0. type, data will only be imported as True or False. This means your source data must have either a 1 or 0 in the column, and cannot use strings for the two values. After importing your data, you can customize the new bit field in Microsoft Dynamics CRM Online and change the values to strings. To work around this limitation, you might want to use Microsoft Dynamics CRM Online to create any new required-bit fields, and then use the Import Data Wizard to import data to the field.
Import Data Wizard uses one input for both the database logical name and the display name; therefore, the database logical name must use ASCII characters. If you use non-English or non-ASCII characters in a name for a custom field, you will get an "Invalid characters in name" error message. To work around this problem, after you import your data, use the Customization area of Microsoft Dynamics CRM Online to change the display name.
The column-header value for a custom field must be 160 or fewer characters. If the column-header value is too long, Import Data Wizard cannot create the custom field, and it fails.