[Q]const char *const * ??

Hi Guys,


When a function has following arg type,
update_data(const char *const *  update_list,...)

exactly what object type update_list   can take?

For example,  I can call update_aaa()  using following variale as an
arg:
const char *updatelist_default[]={ "aaa", "bbb",    NULL};

Then,  why the 2nd 'const' is necessary ?  I mean,
update_data(const char * *  update_list,...)  would work. But actually
not!