Quick search by citation:

5 U.S. Code § 6367 - Receipt and use of leave from a leave bank

(a) An application to receive contributions of leave from a leave bank, whether submitted by or on behalf of an employee—
shall be submitted to the Leave Bank Board of the employing agency of the proposed leave recipient; and
(2) shall include—
the name, position title, and grade or pay level of the proposed leave recipient;
the reasons why leave is needed, including a brief description of the nature, severity, anticipated duration, and, if it is a recurring one, the approximate frequency of the medical emergency involved;
if such Board so requires, certification from 1 or more physicians, or other appropriate experts, with respect to any matter under subparagraph (B); and
any other information which such Board may reasonably require.
If a Board requires that an employee obtain certification under paragraph (2)(C) from 2 or more sources, the agency shall ensure, either by direct payment to the expert involved or by reimbursement, that the employee is not required to pay for the expenses associated with obtaining certification from more than 1 of such sources.
The Leave Bank Board of an employing agency may approve an application submitted under subsection (a).
A leave recipient may use annual leave received from the leave bank established by the employing agency of such employee under this subchapter in the same manner and for the same purposes as if such leave recipient had accrued such leave under section 6303, except that any annual leave and, if applicable, any sick leave accrued or accumulated to the leave recipient shall be used before any leave from the leave bank may be used.
(d) Transferred annual leave—
may accumulate without regard to any limitation under section 6304; and
may be substituted retroactively for any period of leave without pay, or used to liquidate an indebtedness for any period of advanced leave, which began on or after a date fixed by the employing agency of the employee as the beginning of the medical emergency involved.
Except to the extent that the Office of Personnel Management may prescribe regulations, nothing in the provisions of section 7351 shall apply to any solicitation, contribution, or use of leave to or from a leave bank under this subchapter.