This is xnu-8019. See this file in:
RTF_UP          = 0x1
RTF_GATEWAY     = 0x2
RTF_HOST        = 0x4
RTF_REJECT      = 0x8
RTF_DYNAMIC     = 0x10
RTF_MODIFIED    = 0x20
RTF_DONE        = 0x40
RTF_DELCLONE    = 0x80
RTF_CLONING     = 0x100
RTF_XRESOLVE    = 0x200
RTF_LLINFO      = 0x400
RTF_STATIC      = 0x800
RTF_BLACKHOLE   = 0x1000
RTF_PROTO2      = 0x4000
RTF_PROTO1      = 0x8000
RTF_PRCLONING   = 0x10000
RTF_WASCLONED   = 0x20000
RTF_PROTO3      = 0x40000
RTF_PINNED      = 0x100000
RTF_LOCAL       = 0x200000
RTF_BROADCAST   = 0x400000
RTF_MULTICAST   = 0x800000
RTF_IFSCOPE     = 0x1000000
RTF_CONDEMNED   = 0x2000000
RTF_IFREF       = 0x4000000
RTF_PROXY       = 0x8000000
RTF_ROUTER      = 0x10000000