| Conditions | Result | |
| (which & ios::in) != 0 | positions the input sequence | |
| (which & ios::out) != 0 | positions the output sequence | |
| (which & (ios::in | ios::out)) == (ios::in | ios::out) and either way == ios::beg or way == ios::end | positions both the input and the output sequences | |
| Otherwise | the positioning operation fails. |