What does "do." mean in old recipes? I'm reading through a book of cocktails from 1865 and I often seen the measurement for a given ingredient listed as "do.". What does this mean?

Examples:


  40 1/2 ounces of roast and ground cocoa.
  6 2/3 do. ground cardamom seeds.
  6 2/3 do. ground Ceylon cinnamon.
  7 pints of alcohol, 95 per cent.
  20 do. water.


Or:


  2 gallons of ground malt.
  6 do. water, at 142° (degrees) heat.


Or, most bafflingly:


  1 pound = 16 ounces
  1/2 do. = 8 do.
  1/4 do. = 4 do.
I suspect it means "ditto (the above line)":
http://en.wikipedia.org/wiki/Ditto_mark seems to indicate that "do." was an old way of abbreviating before the ditto mark (") became widespread.