With MacPascal's "TEXT WINDOW OUTPUT" option, programs outputting to a text
file may put garbage in the text file when writeln's are used for output.
Here's a workaround: open text output files under program control.
The program may be printing an undefined variable, probably a string variable.
Double check your program for improper variable use. If you determine that
this is not the problem, it is possible that you have run across a bug
reported in versions of MacPascal.