SetErrFile ([cNewFileName]) --> cOldFileName:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Functions:
~~~~~~~~~~
Internal static variable contains a filename of error output. If
performed without a parameters, it returns the file name,
with a parameter it stores it as a new file name for error output.

Parameter description:
~~~~~~~~~~~~~~~~~~~~~~
cNewFileName: new filename for error output

Return value:
~~~~~~~~~~~~~
new filename for error output


Source code is in file  ErrorSys.prg