solutions with non-zero boundary conditions are explicitly classified for all integer powers
p⩾ 1. These solutions are shown to consist of: bright solitary waves and static humps on a
non-zero background for odd p; dark solitary waves on a non-zero background and kink
(shock) waves for even p in the defocusing case; pairs of bright/dark solitary waves on a non-
zero background, and also bright and dark heavy-tail waves (with power decay) on a non …