For optical routes, {HEAD ~ the accumulated data} includes {TAIL ~ signal impairment information}, aggregated from the impairments allocated to each link, along the paths being considered during routing 
includes
For optical routes , { HEAD ~ the accumulated data } includes { TAIL ~ signal impairment information } , aggregated from the impairments allocated to each link , along the paths being considered during routing
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH