# Map "sh" "ch" "ee" to single letters to simplify the parsing.
  gsub(/ch/, "C", x);
  gsub(/sh/, "S", x);
  gsub(/ee/, "E", x);

  # Map platformed and half-platformed letters to capitals to simplify the parsing:
  gsub(/ckh/, "K", x);
  gsub(/cth/, "T", x);
  gsub(/cfh/, "F", x);
  gsub(/cph/, "P", x);
  #             
  gsub(/ikh/, "G", x);
  gsub(/ith/, "H", x);
  gsub(/ifh/, "M", x);
  gsub(/iph/, "N", x);
  #
  gsub(/ck/, "U", x);
  gsub(/ct/, "V", x);
  gsub(/cf/, "X", x);
  gsub(/cp/, "Y", x);
  #
  gsub(/ik/, "A", x);
  gsub(/it/, "B", x);
  gsub(/if/, "I", x);
  gsub(/ip/, "J", x);


   ==
   
  # Unfold letter folding:
  gsub(/A/, "ik", y);
  gsub(/B/, "it", y);
  gsub(/I/, "if", y);
  gsub(/J/, "ip", y);
  #
  gsub(/U/, "ck", y);
  gsub(/V/, "ct", y);
  gsub(/X/, "cf", y);
  gsub(/Y/, "cp", y);
  #
  gsub(/G/, "ikh", y);
  gsub(/H/, "ith", y);
  gsub(/M/, "ifh", y);
  gsub(/N/, "iph", y);
  #
  gsub(/K/, "ckh", y);
  gsub(/T/, "cth", y);
  gsub(/P/, "cph", y);
  gsub(/F/, "cfh", y);
  #
  gsub(/E/, "ee", y);
  gsub(/C/, "ch", y);
  gsub(/S/, "sh", y);