Each window can specify a display table, and so can each buffer.
The window's display table, if there is one, takes precedence over the
buffer's display table. If neither exists, Emacs tries to use the
standard display table; if that is
nil, Emacs uses the usual
character display conventions (see Usual Display).
Note that display tables affect how the mode line is displayed, so
if you want to force redisplay of the mode line using a new display
force-mode-line-update (see Mode Line Format).
This function returns window's display table, or
nilif there is none. The default for window is the selected window.
This function sets the display table of window to table. The argument table should be either a display table or
This variable is automatically buffer-local in all buffers; its value specifies the buffer's display table. If it is
nil, there is no buffer display table.
The value of this variable is the standard display table, which is used when Emacs is displaying a buffer in a window with neither a window display table nor a buffer display table defined, or when Emacs is outputting text to the standard output or error streams. Although its default is typically
nil, in an interactive session if the terminal cannot display curved quotes, its default maps curved quotes to ASCII approximations. See Keys in Documentation.
The disp-table library defines several functions for changing the standard display table.