if (%arg) {									#performed only if obj. arguments given
		my %_temp_hash = _return_attr_data();			#returns list of obj. attributes
		foreach my $argcheck (keys %arg) {				
			next if exists $_temp_hash{"_" . $argcheck};	#checks if attribute exists
			croak "An invalid CD attribute given";		#if not, croaks with error
		}
	}