(a) For the purpose of this chapter and chapter 1407 of this title, a Reserve officer's years of service include all service of the officer as a commissioned officer of a uniformed service other than the following:

(1) Service as a warrant officer.

(2) Constructive service.

(3) Service after appointment as a commissioned officer of a reserve component while in a program of advanced education to obtain the first professional degree required for appointment, designation, or assignment to a professional specialty, but only if that service occurs before the officer commences initial service on active duty or initial service in the Ready Reserve in the specialty that results from such a degree.

(b) The exclusion under subsection (a)(3) does not apply to service performed by an officer who previously served on active duty or participated as a member of the Ready Reserve in other than a student status for the period of service preceding the member's service in a student status.

(c) For purposes of subsection (a)(3), an officer shall be considered to be in a professional specialty if the officer is appointed or assigned to the Medical Corps, the Dental Corps, the Veterinary Corps, the Medical Service Corps, the Nurse Corps, or the Army Medical Specialists Corps or is designated as a chaplain or judge advocate.