1. The FAR references quoted below in pertinent part are applicable to this response.

FAR 13.301 -- Governmentwide commercial purchase card.
(a) Except as provided in 32.1108(b)(2), the Governmentwide commercial purchase card is authorized for use in making and/or paying for purchases of supplies, services, or construction.

(b) Agencies using the Governmentwide commercial purchase card shall establish procedures for use and control of the card that comply with the Treasury Financial Manual for Guidance of Departments and Agencies (TFM 4-4500) and that are consistent with the terms and conditions of the current GSA credit card contract. Agency procedures should not limit the use of the Governmentwide commercial purchase card to micro-purchases. Agency procedures should encourage use of the card in greater dollar amounts by contracting officers … to place orders and/or make payment under other contractual instruments, when agreed to by the contractor. See 32.1110(d) for instructions for use of the appropriate clause when payment under a written contract will be made through use of the card.

FAR 32.1108 Payment by Governmentwide commercial purchase card.
(b)(2)(i) When it is contemplated that the Governmentwide commercial purchase card will be used as the method of payment, and the contract or order is above the micro-purchase threshold, contracting officers are required to verify (by looking in the System for Award Management (SAM)) whether the contractor has any delinquent debt subject to collection under the Treasury Offset Program (TOP) at contract award and order placement. Information on TOP is available at http://fms.treas.gov/debt/index.html.

(b)(2)(ii) The contracting officer shall not authorize the Governmentwide commercial purchase card as a method of payment during any period the SAM indicates that the contractor has delinquent debt subject to collection under the TOP.

2. The following references quoted in pertinent part below are also applicable to this response.

A. DoD Publication: Other Transactions Guide for Prototype Projects, January 2017 (Version 1.2.0)
https://www.dau.mil/tools/t/Other-Transactions-Guide-for-Prototype-Projects

C2.1.1.6. Competition. 10 U.S.C. §2371b (Section 2371b) requires that competitive procedures be used “to the maximum extent practicable,” but the Competition in Contracting Act is not applicable to OTs [Other Transactions]. Competitions for OTs should be structured in a common sense manner that treats offerors fairly and, when applicable, be consistent with industry practice for that market segment. The multi-functional acquisition team is responsible for maximizing competition.

C2.1.1.6.1. Publication. Agreements Officers should publish opportunities where they are most likely to reach solution providers. This includes publishing opportunities outside traditional Government venues—beyond the Government-wide entry point (i.e., FedBizOpps).

C2.1.1.6.2. Solicitation Methods. Innovation is encouraged for identifying and competitively selecting sources. Agencies who intend to award only OTs off a solicitation are free to create their own process to solicit and assess potential solutions provided it is a fair process and the rationale for making the Government investment decision is documented.

B. GAO Principles of Federal Appropriations Law, Vol I, Jan 2004, GAO-04-261SP
https://www.gao.gov/products/GAO-04-261SP

The “Necessary Expense” Doctrine (p. 4-20 – 4-22). The spending agency has reasonable discretion in determining how to carry out the objects of the appropriation. This concept [is] known as the “necessary expense doctrine”. When applying the necessary expense rule, an expenditure can be justified after meeting a three-part test:
  1. The expenditure must bear a logical relationship to the appropriation sought to be charged. In other words, it must make a direct contribution to carrying out either a specific appropriation or an authorized agency function for which more general appropriations are available.
  2. The expenditure must not be prohibited by law.
  3. The expenditure must not be otherwise provided for, that is, it must not be an item that falls within the scope of some other appropriation or statutory funding scheme.

3. As stated in reference 2A above, innovative approaches are encouraged to maximize competition as required by 10 U.S.C. §2371b which authorizes the use of Other Transactions (OTs). Therefore to best meet this statutory requirement, DoD OT Guide section C2.1.1.6.1 strongly encourages acquisition teams to publish OT opportunities where they are most likely to reach solution providers, including publishing opportunities outside traditional Government venues—beyond the Government-wide entry point (i.e., FedBizOpps). Consequently, posting the contemplated OT opportunity in a journal such as Space News, Defense News, or similar publication would be completely proper under this current DoD guidance.

4. Furthermore, given this express guidance as set forth in the DoD OT Guide for soliciting competition “to the maximum extent practicable” as required by 10 U.S.C. §2371b, procuring advertising services from such publications would appear to be compliant with the “Necessary Expense” doctrine for the use of appropriations as established by fiscal law and as interpreted by a long line of GAO opinions described in reference 2B above.

5. Based on the foregoing rationale, we would agree that using the Governmentwide Commercial Purchase Card (GPC) to procure advertising services for the contemplated OT opportunity from such publications in order to increase the likelihood of reaching as many potential solution providers as possible would be appropriate, provided that the contracting officer complies with the procedures set forth in FAR 13.301 and in FAR 32.1108 as summarized above in making such a GPC purchase.