Which platform does not allow multiple FileWriters to open on a file

Which platform does not allow multiple FileWriters to open on a file

JAVA docs for FileWriter say
Whether or not a file is available or may be created depends upon the *
underlying platform. *Some platforms, in particular, allow a file to be *
opened for writing by only one* FileWriter (or other file-writing *
object) at a time. In such situations the constructors in this class *
will fail if the file involved is already open."
I need to know what are the platforms which does not allow multiple
FIleWriter on a file.
Thanks