Description

   The decc$feature_get_value function retrieves a value for the
   feature specified by index. The mode determines which value is
   returned.

   The default value is what is used if not set by a logical name or
   overridden by a call to decc$feature_set_value.

   If mode = 4, then the initialization state is returned. Values
   for the initialization state are:

      0 not initialized
      1 set by logical name
      2 forced by decc$feature_set_value
      -1-initialized to default value

   On error, -1 is returned and errno is set to indicate the error.

   See also decc$feature_get, decc$feature_get_index, decc$feature_
   get_name, decc$feature_set, decc$feature_set_value, decc$feature_
   show, and decc$feature_show_all.