(54)Directive 2009/138/EC provides for the possibility for insurance and reinsurance groups to calculate their Solvency Capital Requirement with a full or partial internal model subject to prior supervisory approval. Any integration technique of a partial internal model into the standard formula to calculate the group Solvency Capital Requirement is part of that internal model and is to, together with the other components of the partial internal model, to comply with the relevant requirements of Directive 2009/138/EC. The integration techniques set out in Annex XVIII to Delegated Regulation (EU) 2015/35 are primarily designed for the integration of risks and not for the integration of entire undertakings within an internal model at group level. Therefore, it should be specified that in cases where undertakings are integrated as a whole, Article 239(4) of that Regulation applies.