  A packing function on a set Omega in R^n is a one-to-one correspondence
between the set of lattice points in Omega and the set N_0 of nonnegative
integers. It is proved that if r and s are relatively prime positive integers
such that r divides s-1, then there exist two distinct quadratic packing
polynomials on the sector {(x,y) \in \R^2 : 0 \leq y \leq rx/s}. For the
rational numbers 1/s, these are the unique quadratic packing polynomials.
Moreover, quadratic quasi-polynomial packing functions are constructed for all
rational sectors.
