Summary of the Diffractive Working Group at DIS98
  Recent experimental and theoretical developments in the understanding of high energy diffraction, presented in the working group on diffraction at DIS98 in Brussels, are summarised. A template, giving the definition of the most commonly used kinematical variables in diffraction, which was provided in the working group sessions, is reproduced as a appendix. References to original papers may be found within the individual contributions. 
A. Goussiou, M. McDermott, N.N. Nikolaev, R. Roosen, K. Piotrzkowski