This paper deals with a well known problem in AI planning: detecting and resolving conflicts in nonlinear plans. We sketch a theory of restricted conflict detection and resolution that subsumes conflict handling in classical nonlinear planners. By relaxing the restrictions, we develop a more general concept of conflicts suggesting practical and theoretical limitations of conflict handling in nonlinear plans. 1 The problem Nonlinear planning was invented [Saccrdoti, 1977, Tate, 1977] as a lea,st commitment strategy for operator ordering. A nonlinear plan specifies a strict partial ordering on operators that can be interpreted to represent every linear ordering compatible with it. (Note that NOAH [Saccrdoti, 1977], e.g., uses a specialization of this interpretation as it does not allow every compatible linear ordering but considers ordering whole branches only.) While being efficient in that it allows whole areas of the space of linear plans to be searched at once, nonlinear planning po...