CloudExtend Excel respects the required fields of the form selected (or the default form if a custom form was not selected). To see which fields are required refer to your NetSuite form (create a blank new record). Enter in a value in the entity field and press tab. Fields with an asterisk that are empty are required. Fields with an asterisk that are pre-filled have default values. Leaving this empty in CloudExtend Excel during an upload will result in the default value being populated. Save time and leave these values empty if you plan on uploading default values.
In the example below (vendor bill) the blue fields are required and the orange fields, while required, will autofill with default values and can generally be left empty during an update.