This read-create IpAddress is part of the composite index (with vRtrID and vRtrSvcIpRangeMask) identifying an IP address range assigned to a virtual router's service interface. Admins use it, together with the mask, to define one of potentially several service IP address ranges bound to a single interface on a virtual router. For example, setting it to 10.10.0.0 alongside a /24 mask would define the 10.10.0.0/24 range as a service IP range for that interface.