Except as otherwise provided in subsection (d)(5), assignments under this section may not exceed four years of continuous service for any member of the Service unless the Secretary approves an extension of such period for that member because of special circumstances.
22 U.S. Code § 3983. Assignments to non-Service and other positions
(a) Positions assignableThe Secretary may (with the concurrence of the agency, organization, or other body concerned) assign a member of the Service for duty—
with a domestic or international trade, labor, agricultural, scientific, or other conference, congress, or gathering;
for special instruction, training, or orientation at or with a public or private organization; and
(b) Salary; travel and other expenses
The salary of a member of the Service assigned under this section shall be the higher of the salary which that member would receive but for the assignment under this section or the salary of the position to which that member is assigned.
The salary of a member of the Service assigned under this section shall be paid from appropriations made available for the payment of salaries and expenses of the Service. Such appropriations may be reimbursed for all or any part of the costs of salaries and other benefits for members assigned under this section.
(c) Length of assignment
(d) Assignment to the American Institute in Taiwan
(3) In this subsection, the term “employee” does not include—
a noncareer appointee, limited term appointee, or limited emergency appointee (as such terms are defined in section 3132(a) of title 5) in the Senior Executive Service; or
An assignment or detail under this subsection may be made with or without reimbursement from the American Institute in Taiwan.
The period of an assignment or detail under this subsection shall not exceed a total of 6 years, except that the Secretary (or any other head of a department or agency of the United States, with the concurrence of the Secretary) may extend the period of an assignment or detail for an additional period of not more than 6 years.