std::ios_base(3cxx) on Linux
The text a2c80766ca5d, as Debian 10 (Buster) shipped it.
The base of the I/O class hierarchy. This class defines everything that can be defined about I/O that does not depend on the type of characters being input or output. Most people will only see ios_base when they need to specify the full name of the various I/O flags (e.g., the openmodes).