The DHCP_IP_RESERVATION structure defines an IPv4 reservation for a DHCPv4 client. This is used in structure DHCP_SUBNET_ELEMENT_DATA (section 2.2.1.2.33).

 typedef struct _DHCP_IP_RESERVATION {
   DHCP_IP_ADDRESS ReservedIpAddress;
   DHCP_CLIENT_UID* ReservedForClient;
 } DHCP_IP_RESERVATION,
  *LPDHCP_IP_RESERVATION;

ReservedIpAddress: This is of type DHCP_IP_ADDRESS (section 2.2.1.2.1) that contains the IPv4 address of the DHCPv4 client for which a reservation is created.

ReservedForClient: This is a pointer of type DHCP_CLIENT_UID (section 2.2.1.2.5) that represents the DHCPv4 client identifier (section 2.2.1.2.5.1).