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QUOTE
1.401(k)-1(f)(4) Designated Roth contributions must satisfy rules applicable to elective contributions
(i) In general. --A designated Roth contribution must satisfy the requirements applicable to elective contributions made under a qualified cash or deferred arrangement. Thus, for example, a designated Roth contribution must satisfy the requirements of paragraphs (c) and (d) of this section and is treated as an employer contribution for purposes of sections 401(a), 401(k), 402, 404, 409, 411, 412, 415, 416 and 417. In addition, the designated Roth contributions are treated as elective contributions for purposes of the ADP test. Similarly, the designated Roth account under the plan is subject to the rules of section 401(a)(9)(A) and (B) in the same manner as an account that contains pre-tax elective contributions.