In this paper, we present a construction of improved geometric Goppa c
odes which, for the case of r<2g, are often more efficient than the cu
rrent geometric Goppa codes derived from some varieties, which include
algebraic curves, hyperplanes, surfaces, and other varieties. For the
special case of a plane in a three-dimensional projective space, the
improved geometric Goppa codes are reduced to linear multilevel codes.
For these improved geometric Goppa codes, a designed minimum distance
can be easily determined and a decoding procedure which corrects up t
o half the designed minimum distance is also given.