...
Open a file named <filename> for writting writing access. By default access is "w", but is possible to use "a" to append to a previous file (and "wb" or "ab" to open the file in binary mode). It returns a long integer <file_id> representing the channel
...
Print data from a Tcl procedure in a file opened with GiD_File fopen and returns the number of printed characters.
(a .bas template implictly implicitly open/close a file with this command, and the file_id could be send to a tcl procedure as a parameter with the *FileId template keyword)
<file_id> must be a valid file descriptor, that could be obtained in a .bas template with the *FileId command (or with GiD_File fopen)
<format> must be a valid C/C++ format, according with the arguments
return
...