-/* A system call that opens a file identified by name in a given mode, and
- returns a file descriptor uniquely identifying that file.
+
+/* stdio.h */
+
+/* A system call that opens a file identified by name in a given mode. Return
+ a file descriptor uniquely identifying that file.
+ (The mode is the return value of the _PDCLIB_filemode() function.)
+*/
+_PDCLIB_fd_t _PDCLIB_open( char const * const filename, unsigned int mode );
+
+/* A system call that writes a stream's buffer.
+ Returns 0 on success, EOF on write error.
+ Sets stream error flags and errno appropriately on error.