Urgent warning!

An error has been found in one of the MarkSim data files. Some of the
cluster correlation matrices are singular. This has been corrected. To
update your installation download the file avmats.cor from the ICASA web
site http://www.icasa.net/dssat/downloads.html and replace the existing one
in your directory \markdat\. Rest assured that if you haven't noticed
MarkSim crash with an error message for an arithmetic exception then you
haven't encountered the problem and all your simulations will have been
correct. The singular correlation matrices result in MarkSim trying to take
a square root of a negative number and the simulation stops. The clusters
affected are rare ones and haven't showed up in over 4 years of testing and
work with MarkSim.