| Mode | Read | Write | Pointer at | Truncate to zero | create new |
| r | y | n | beginning of the file | n | n |
| r+ | y | y | beginning of the file | n | n |
| w | n | y | beginning of the file | y | If it does not exist |
| w+ | y | y | beginning of the file | y | If it does not exist |
| a | n | y | end of the file | n | If it does not exist |
| a+ | y | y | end of the file | n | If it does not exist |
| x | n | y | beginning of the file | not rquired | always |
| x+ | y | y | beginning of the file | not required | always |
| c | n | y | beginning of the file | n | If it does not exist |
| c+ | y | y | beginning of the file | n | If it does not exist |