Hi,

I have read config(9), had a look at gram.y in usr.sbin/config/
(not much experience with yacc, though) and still have some small questions.

  - config(9) describes a way to add simple flag options (defflag,
    defparam). Without a filename parameter the option is defined on
    the commandline with -D. From this I would expect _every_ option
    to be defined somewhere in a device definition file. But I have
    seen kernel configuration files using options _without_ a definition
    in a config file, resulting in -D definitions in the compiler
    commandline.
    Is this recommended or simply tolerated ?

  - it seems as if every option in a kernel configuration file also turns
    automatically into an attribute (in lower case) ?

  - 'file' definitions can have complex attribute combinatons ( (a | b) & ! c) 
    This is not mentioned in the man page and I found it in gram.y.
    If this is correct, I could add this to config(9).

  - I found no explanation for the optional 'rule' parameter in 'file'
    definitions. How and for what purpose can it be used ?
    
ciao
     Klaus