Command status and result code. Zero indicates success, +1 indicates format operation is in progress and -1 indicates a FORMAT failure. The COPY command provides the following set of failure indications:
-1 Incorrect number of arguments found on command line.
-2 Buffer memory allocation failed.
-3 Unable to open the source file.
-4 Unable to create the destination file.
-5 Unable to create the destination file due to root directory being full.
-6 Source file read failed.
-7 Destination file write failed.
The user may want to preset this to some value like -99 in order for there to be a positive indication that the desired operation has been started