Truncate an opened file to the specified size. The first argument Has to be the file number used in the OPEN statement opening the file. The second argument is the number of records to be in the file after it is truncated.
The size of a record has to be specified when the file is opened. If the size Of a record is not specified in number of bytes then the command TRUNCATE Does truncate the file to the number of specified bytes instead of records. (In other words the record length is one byte.)
When the file is actually shorter than the length specified by the command argument the command TRUNCATE automatically extends the file padding with bytes containing the value 0.