Opens a data channel.
Open pathname For mode [Access io] [locking] As [#]filenum [Len=recLen]
pathname: Path and name of the file to open. If you try to read a file that does not exist (Access = Read), an error message appears. If you try to write to a file that does not exist (Access = Write), a new file is created.
mode: Keyword that specifies the file mode. Valid values: Append (append to sequential file), Binary (data can be accessed by bytes using Get and Put), Input (opens data channel for reading), Output (opens data channel for writing), and Random (edits relative files).
io: Keyword that defines the access type. Valid values: Read (read-only), Write (write-only), Read Write (both).
locking: Keyword that defines the security status of a file after opening. Valid values: Shared (file may be opened by other applications), Lock Read (file is protected against reading), Lock Write (file is protected against writing), Lock Read Write (denies file access).
filenum: Any integer expression from 0 to 511 to indicate the number of a free data channel. You can then pass commands through the data channel to access the file. The file number must be determined by the FreeFile function immediately before the Open statement.
recLen: For Random access files, set the length of the records.
You can only modify the contents of a file that was opened with the Open statement. If you try to open a file that is already open, an error message appears.
If the Open statement tries to open a file to which the current user does not have read/write permissions, an I/O error will be raised.