De wichtigste bsundare Flechnoaheit is da acre,wo 1 furlong × 1 chain (oda am Fejdstroafn vo 1 × 0,1 furlong) entspricht. Dees san 40 rods × 4 rods oda 10 square chains, damit 10·222 = 4840 square yards = 4047 m2; 640 acres eagebm a square mile. Beochtn muass ma owa, dass dena Gressn in de USA i. d. R. weida afn survey inch basian, oisa a wengal gressa san (zwoate Ogob).