In order for OOF, SO or Multi-cloud to determine which cloud should be used to deploy a VNF, the resources required for that VNF must be understood and preferably reserved.  An ETSI SOL001 compliant VNF may have several flavors and for each flavor may have several scaling aspects.  As SO chooses to deploy or scale a VNF, it will select a particular flavor and/or scaling aspect of the VNF The SO will need to calculate the required resources of the flavor or scaling aspect so that OOF can determine which cloud to use or if the resources are available on the original cloud respectively.