Fellowships may be awarded for periods of varying length, not exceeding one 12-month period of actual training and research and may be extended for not exceeding the same periods in the manner prescribed under § 255.3 and subject to the availability of appropriations. Fellowships may be cancelled for cause by the Director of the National Institute of Standards & Technology, with the approval of the Secretary of Commerce and the Secretary of State, or the duly authorized representative of the Secretary of State.