ZW - ignore file contents.

zw: Says you don't care about the contents of the file. ACC.FIL will remove temporary files of the same name from the AFT if necessary to create a file of the correct initial size. "zw" is implied automatically when you use the "b" option or "w" without "wr". "zw" should be used in all cases when the old file contents will not be needed (e.g. when you intend to overwrite the existing contents).