What is the process for the Army to purchase these services off of the DoD contract and what part of the FAR/DFAR supports this process?
Information on the process for purchasing these services off of a not yet awarded DoD contract is not currently available. In response to your other question regarding what part of the FAR/DFARS supports this process, FAR Subpart 17.5 Interagency Acquisitions
and DFARS Subpart 217
.5 Interagency Acquisitions under the Economy Act
provide guidance on this process.
The FAR reference you cited in your additional background information, (FAR Subpart 17.2
) is regarding options.
No further information is available regarding the pending DoD IT services contract you referred to in your request. Presumably, specific information on the availability of this contract vehicle for use by other agencies outside the military will become available after contract award. We recommend you wait until after contract award and contact the contracting officer for additional information on its availability for use by other agencies outside the military. Meanwhile, you may want to refer to the Interagency Contract Directory (ICD), a central repository of Indefinite Delivery Vehicles (IDV) awarded by the Federal agencies where the IDV is available for use at both the intra agency and interagency levels. The website address is: https://www.contractdirectory.gov/contractdirectory/