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Linear Collider Colleagues: Those who have been using my lcdtrk.f tracking error estimation routine, are tables generated from it, be aware that I have found an algorithmic error in the coordinate transformation from the barrel to the disk systems (and vice-versa). This mistake leads, in rare cases, to an error matrix which is not positive definite. The mistake seems to have very little effect on the output of the program for most configurations I tests -- the only difference I saw was for tracks which involved mixed barrel and disk material layers, but only barrel-geometry measurement layers. Nevertheless, to be absolutely certain that the output is correct, one must run with the amended version, available via downlaod from http://www.slac.stanford.edu/~schumm The file of interest is the latest version: lcdtrk20000928.tar.gz. This contains the new fortran source code, as well as all the old stuff (the .txt documentation file has been updated to include comments about the mistake and its correction). - Bruce