Histogram of the spatial distribution of satellite debris from the F07 GSS formation model in M31-centric coordinates (Section 4). We show the spectroscopic field locations (colored rectangles) and photometric NE and W shelf edges (black points) from Figure 1 in addition to stream PN candidates (Merrett et al. 2003, 2006). The simulated NE shelf region (black outlined box) is defined using X _M31 > 0.2° and −1.5° < Y _M31 < 0.5°, where X _M31 and Y _M31 are defined along the NE major axis (P.A. = 38° E of N) and NW minor axis, respectively.