integer_handler= open (text_filespecs);
Open file for read and write operations. If the file already exists, it is open for appending data and the file pointer is positioned at the end of the existing data. If the file does not exist, it is automatically created and the file pointer is positioned at the beginning of the file.
The “filespecs” parameter specifies path and name: “device:/dir/…/filename”
File handler number is returned in case of success, or a negative value in case of a failure.