de modo decimandi

Of the manner of tithing. A discharge by custom or prescription is where, time out of mind, certain persons or lands have been discharged from the payment of tithes. This immemorial usage is either de modo decimandi or de non decimando. A modus decimandi, often called a "modus," is any means whereby the general law of tithing is altered, and a new method of taking them is introduced. A prescription de non decimando is a claim to be entirely discharged of tithes, and pay no compensation in lieu of them. See 2 Bl Comm 29, 31.