This variable causes the system's buffers to be flushed on the first WRITE, REWRITE, or DELETE that occurs after an indexed file is opened for I/O. The purpose of this is to update the "user count" field in the file's header to keep it accurate. When this variable is set to "1" (on, true, yes), this feature is turned on; when set to "0" (off, false, no), it's turned off. The default setting is "0" except for MS-DOS systems, where it is "1".