The first arg is an object or a file_name.
The second (optional) arg flags specifies, what info is to be returned (function names, or return types, or number of args the functions takes, ...), and also, if info is wanted about all functions, or just about public/private/varargs/... functions. The interpreter source should contain a <mudlib/sys/lpctypes.h> and <mudlib/sys/functionlist.h> that define the values for the flags and the returntypes of functionlist().
Currently (3.2.1@40) the following symbolic values for the flag are #defined, which can be ored together
RETURN_FUNCTION_NAME RETURN_FUNCTION_FLAGS RETURN_FUNCTION_TYPE RETURN_FUNCTION_NUMARG RETURN_FUNCTION_ARGTYPE /* not implemented */
Also, if flags has TYPE_MOD_PRIVATE in it, then private functions will not be shown. If flags has TYPE_MOD_STATIC in it, then both private and static functions will not be shown. If flags has TYPE_MOD_PROTECTED in it, then both static and protected functions will not be shown. If flags has NAME_HIDDEN in it, then functions which are private when inherited will not be shown.