; (3) the National Science Foundation; (4) the Department of Commerce; (5) the Department of the Interior; (6) the Environmental Protection Agency; and (7) not more than 2 additional agencies, which the Director of the Office of Personnel Management may designate, that have significant numbers of employees in positions that require skills in science, technology, engineering, or mathematics. (c) Participation The head of each agency referred to in subsection (b) may determine whether the agency will participate in the personnel demonstration project under this section, and, if the agency head determines that the agency will so participate, whether the project will apply to current employees of that agency, current employees of 1 or more components of that agency, newly hired employees of that agency, or newly hired employees of 1 or more components of that agency. (d) Duration and size of project (1) In general Except as provided in paragraph (2), the demonstration project under this section shall be carried out for a 10-year period beginning on the date of enactment of this Act. (2) Extension The Director of the Office of Personnel Management may extend the demonstration project under this section for an additional 10-year period. (3) Total number of employees The total number of Federal employees included in the demonstration project in any 1-year period may not exceed 10 percent of the total number of Federal civilian employees in all Executive agencies (as defined in section 105 of title 5, United States Code) in the preceding 1-year period. (e) Authorization of appropriations There are authorized to be appropriated such sums as may be necessary to carry out this section. 375. Development of proposal for simplified personnel system for Veterans Health Administration (a) In general The Secretary of Veterans Affairs shall develop a legislative proposal to establish, under title 38, United States Code, a single personnel system that— (1) applies to all positions in the Veterans Health Administration