(%-constructs are allowed when the string is the entire mode-line-format\n\
or when it is found in a cons-cell or a list)\n\
%b -- print buffer name. %f -- print visited file name.\n\
+ %F -- print frame name.\n\
%* -- print %, * or hyphen. %+ -- print *, % or hyphen.\n\
% means buffer is read-only and * means it is modified.\n\
For a modified read-only buffer, %* gives % and %+ gives *.\n\