create a %hash
open fileA
while get a line from fileA
  parse out the three important fields from the line
  concat those fields into a single string
  put that string in the hash as a key, with the line as its value
close fileA
open fileB
while get a line from fileB
  parse out the three important fields from this line
  concat those fields into a single string
  if that string exists as a key in the hash
     print out this line and the value of the matching hash key
close fileB