Is a writ of habeas corpus ad prosequendum a "detainer" under the Detainer Act?

Thus we are asked to take a hypothetical and possibly non-existent conflict between a minor provision of the Act which relates to transfer mechanics (the Art. IV(a) proviso) and prior federal law (28 U.S.C. 2241) and to use it as the touchstone for an interpretation of the rest of the Act that would vitiate its operation insofar as it affects federal detainers, since virtually all federal transfers are conducted pursuant to the writ. ²⁷ This, in turn, would substantially impair the operation of the Agreement as a whole, since federal detainers form a large percentage of all detainers outstanding. ²⁸ Given this choice, we are constrained to hold that, whether or not a writ of habeas corpus ad prosequendum constitutes a "detainer," see United States v. Mauro, supra, once a federal detainer has been lodged against a state prisoner the habeas writ constitutes a "written request for temporary custody" within the meaning of Article IV of the Detainers Act.

Turning to whether the government violated the limitations of the Act in this case, Article IV(e) provides: