In addition to the somewhat unpredictable set of changes, the patterns involved in weakening are further complicated by the fact that some suffixes weaken stops but do not affect fricatives. Boas lists 11 suffixes weakening stops and affricates but not fricatives; these suffixes are indicated by the notation (=) as seen in the following list: (=) "continuously"; (=) "mouth, opening, to talk about"; (=) "away"; (=) or (=) "to do something while doing something else" – weakens ; (=) "continuing motion in a definite direction" – weakens , , ; (=) "to go attend, to be on the way"; (=) "place where there are many (plants etc.)" – does not weaken ; (=) "canoe"; (=) "in front of house, body, mountain"; (=) "by force"; (=) "moving on water".