Demi-mark
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
Half a mark ; a sum of money which was anciently required to be tendered in a writ of right, the effect of such tender being to put the demandant, in the first instance, upon proof of the seisin as stated in his count; that is, to prove that the seisin was in the king's reign there stated.
Rose. Real Act. 216.