17.31—Duty periods defined.
Definitions of duty periods applicable to eligibility for medical benefits are as follows:
(d) Inactive duty training.
The term inactive duty training means: (1) Duty (other than full-time duty) prescribed for Reserves (including commissioned officers of the Reserve Corps of the Public Health Service) by the Secretary concerned under section 206, title 37 U.S.C., or any other provision of law;
(2)
Special additional duties authorized for Reserves (including commissioned officers of the Reserve Corps of the Public Health Service) by an authority designated by the Secretary concerned and performed by them on a voluntary basis in connection with the prescribed training or maintenance activities of the units to which they are assigned.
(3)
Duty (other than full-time duty) for members of the National Guard or Air National Guard of any State under the provisions of law stated in paragraph (c)(3) of this section.
(4)
Inactive duty for training does not include work or study performed in connection with correspondence courses, or attendance at an educational institution in an inactive status, or duty performed as a temporary member of the Coast Guard Reserve.