27 Input/output library [input.output]

27.2 Iostreams requirements [iostreams.requirements]

27.2.2 Positioning type limitations [iostreams.limits.pos]

The classes of Clause [input.output] with template arguments charT and traits behave as described if traits::pos_type and traits::off_type are streampos and streamoff respectively. Except as noted explicitly below, their behavior when traits::pos_type and traits::off_type are other types is implementation-defined.

In the classes of Clause [input.output], a template formal parameter with name charT represents a member of the set of types containing char, wchar_t, and any other implementation-defined character types that satisfy the requirements for a character on which any of the iostream components can be instantiated.