The lattice orders on R-n that are compatible with the vector space st
ructure are characterized in terms of bases of R-n. The index of the e
lements of a space R-n equipped with a compatible lattice order is int
roduced, and used to characterize isotone linear operators acting on s
paces with given compatible lattice orders. (C) 1998 Elsevier Science
Inc. All rights reserved.