Bearer authentication header of the form Bearer <token>, where <token> is your auth token.
The custom field ID
255custom1_str, custom2_str, custom3_str, custom4_str, custom5_str, custom1_int, custom2_int, custom3_int, custom4_int, custom5_int, custom1_dec, custom2_dec, custom1_datetime, custom2_datetime, custom3_datetime, custom4_datetime, custom5_datetime, foreign_id 255CustomFieldResource