netboot.xyz/ipxe/local/general.h

#define DIGEST_CMD            /* Image crypto digest commands */
#define DOWNLOAD_PROTO_HTTPS  /* Secure Hypertext Transfer Protocol */      
#define IMAGE_COMBOOT         /* COMBOOT */
#define IMAGE_TRUST_CMD	      /* Image trust management commands */
#define NET_PROTO_IPV6        /* IPv6 protocol */
#define VLAN_CMD              /* VLAN commands */