private function addQueryLine ($rel, $col, $test, $value) {
		// Check tests are usable
		if (!in_array($test, array('!=', '>=', '<=', '<', '>', '=', 'like'))) {
			throw new \Exception('Unrecognized query parameter. Please use <,>,=,>=,<=, != or like');
		}

		// Make sure $rel is lower-case
		$rel = strtolower($rel);

		$test = str_replace(array('!=', '>=', '<=', '<', '>', '=', 'like'), array('Neq', 'Geq', 'Leq', 'Lt', 'Gt', 'Eq', 'Contains'), $test);

		// Create caml
		$caml = $this->where_caml;
		$content = '<FieldRef Name="' . $col . '" /><Value Type="Text">' . htmlspecialchars($value) . '</Value>' . PHP_EOL;
		$caml .= '<' . $test . '>' . $content . '</' . $test . '>';

		// Attach relations
		if ($rel == 'and') {
			$this->where_caml = '<And>' . $caml . '</And>';
		} elseif ($rel == 'or') {
			$this->where_caml = '<Or>' . $caml . '</Or>';
		} elseif ($rel == 'where') {
			$this->where_caml = $caml;
		}

		// return self
		return $this;
	}