This is essentially the complement of cardInUseVCs: the remaining VC table capacity available for new circuits on this card. Because provisioning systems often check this value directly before attempting a new PVC setup, a cardFreeVCs reading near zero is the direct, real-time cause of no-resources-available errors when trying to add circuits to that card. For example, cardFreeVCs reporting 0 explains why a provisioning attempt on that card fails with a resource-exhaustion error even though the port itself still has physical bandwidth available.