Defines starting with `a' in bsd/netinet

• arp_hln bsd/netinet/if_ether.h:133
• arp_hrd bsd/netinet/if_ether.h:131
• arp_op bsd/netinet/if_ether.h:135
• arp_pln bsd/netinet/if_ether.h:134
• arp_pro bsd/netinet/if_ether.h:132