25.156. SEEK fn,position
Go to a specified position in an open file. You can use this command to position the file pointer to a specific position. The next read or write operation performed on the file will be performed on that very position that was set using the command SEEK. The first argument is the file number that was used in the statement OPEN to open the file. The second argument is the position where the file pointer is to be set.
The position is counted from the start of the file counting records. The actual file pointer will be set after> the record position. This means that if for example you want to set the file pointer To the start of the file then you have to SEEK fn,0. This will set the File pointer before the first record.
If there was no record length specified when the file was opened the counting takes bytes. There is no special "record" structure of a file as it is usually under UNIX or Windows NT. The record is merely the number of bytes treated as a single unit specified during file opening.