From a downloaded document.

Annex II. Notarised statement template in the event that the bidder demonstrates the required solvency and/or the required commitment to allocate resources by relying on the solvency and/or resources of other organisations. [NOTE: To be presented only in the event that the bidder has submitted the best tender, and in the event that the bidder, to prove the required solvency and/or the commitment to assign the required resources, intends to base such solvency and/or resources on those of other organisations. It must be completed by the third party organisation].

Artículo 63. Integración de la solvencia con medios externos.
Para acreditar la solvencia necesaria para celebrar un contrato determinado, el empresario podrá basarse en la solvencia y medios de otras entidades, independientemente de la naturaleza jurídica de los vínculos que tenga con ellas, siempre que demuestre que, para la ejecución del contrato, dispone efectivamente de esos medios.

https://www.boe.es/buscar/act.php?id=BOE-A-2011-17887

b) Que el PCAP permite, cláusula 9.4, la acreditación de la solvencia con medios externos, de tal manera que AMBUNOVA presentó el compromiso de cesión de solvencia técnica de dos sociedades integradas en su grupo empresarial: [name of company] y [name of company] justificándose así convenientemente el cumplimiento del requisito de solvencia técnica, al margen de la clasificación revocada. Aportó además el compromiso de la sociedad [name of company] de cesión a [name of company] de su clasificación en el grupo R, subgrupo 2, categoría D, en caso de resultar adjudicataria.

http://www.boa.aragon.es/cgi-bin/ACTA/BRSCGI?CMD=VEROBJ&MLKO...

Figure 5. Solvency requirement for companies bidding as part of a temporary consortium.
In the case of companies bidding in consortia, as the CNC has stated before, the requirement for each company individually to meet the required criteria for technical ability and economic solvency may amount to an “unnecessary and unwarranted restriction, since when a temporary consortium submits a tender the important thing is for it to be capable, as an economic unit, of fulfilling the requirements made of it. Precisely one of the reasons for which temporary consortia are established to take part in tender processes is to bring together the experience, technical ability and economic/financial solvency of different economic operators, thus making access to tender processes possible for companies that would not be able to compete individually. Imposing the requirements on each member of the temporary consortium involves unnecessarily restricting the ability of many companies to participate in the tender processes and thereby erecting unwarranted obstacles to competition.” (CNC, Res. S/0272/10, FJ 2º, underlining added).

https://www.cnmc.es/sites/default/files/2120603_0.pdf

I understand what it is but I'm afraid I can't find a translation.

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Note added at 2 hrs (2020-10-25 19:59:14 GMT)
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There are quite a few references for 'resource allocations'.

2.3.Selection criteria
Tenderers must be in a stable financial position and prove their economic, financial, technical and professional capacity to carry out the work subject to this call for tender. The tenderer may rely on the capacities of other entities, regardless of the legal nature of the links which it has with them. It must in that case prove to the Contracting Authority that it will have at its disposal the resources necessary for performance of the contract, for example by producing an undertaking on the part of those entities to place those resources at its disposal.

https://ec.europa.eu/transport/sites/transport/files/facts-f...