1. The variable $lterm is used both for input and output. Note that
   changing $lterm does NOT mark buffers as changed.
2. show-files and filename completion both skip directories.
3. Buffer name completion will ignore invisible buffers.
4. Input of file, buffer, or command names can include any character.
   The most obvious example is space. To enter a character literally,
   type ^Q followed by the character.
5. Buffers maintain a "file type", which is set and checked via the
   $cftype variable. When setting, any OS format can be used (&FFF,
   text, 2_111111111111, etc). When checking, the value is given in
   decimal.
6. Setting $cbflags works correctly - ie, you can set a buffer to be
   invisible, and the buffer is not always marked as changed, even if
   you just set the changed flag off!
