In this case, {HEAD ~ the file} includes content instances, {TAIL ~ each content instance} being associated with a respective field, and each field having a respective type 
In this case , { HEAD ~ the file } includes content instances , { TAIL ~ each content instance } being associated with a respective field , and each field having a respective type
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH