Fluke Calibration’s policy regarding calibration interval of instruments built, sold, and serviced by Fluke Calibration is to follow ISO/IEC 17025 guidelines as stated with the following section from the ISO/IEC 17025 guide:
5.10.4.4 A Calibration certificate (or calibration label) shall not contain any recommendation on the calibration interval except where this has been agreed with the customer. This requirement may be superseded by legal regulations.
Therefore, our policy is to the leave the calibration interval "Undefined" unless the customer asks for a particular calibration interval.