The central interface to the buffers is formed by three pointers for each of the two buffers. The
pointers returned from the functions eback(), gptr(), and egptr() form the interface to the read
buffer. The pointers returned from the functions pbase(), pptr(), and epptr() form the interface
to the write buffer. These pointers are manipulated by the read and write operations, which may
result in corresponding reactions in the corresponding read or write channel. The exact operation is
examined separately for reading and writing.