48 C.F.R. § 1601.102
(b) The FEHBAR does not replace or incorporate regulations found at 5 CFR part 890, which provides the substantive policy guidance for administration of the FEHBP under 5 U.S.C. Chapter 89. The following is the order of precedence in interpreting a contract provision under the FEHBP:
[52 FR 16037, May 1, 1987, as amended at 59 FR 14764, Mar. 30, 1994]