Figure vsg.4 : First-order Diffraction Efficiency Trends. The dashed lines represent the efficiency derived from the first X-GEF test carried out on the facet, representative of the flight-grating X-GEF tests. Relative changes in measured diffraction efficiency for subsequent tests are shown; the dotted lines represent efficiency variations of +/- 10% of the initial value. Some facet measurements of note are indicated with the grating name. See the HEG and MEG First-order Efficiency Plot Anomalies sections of the text for a list and discussion of anomalies in these trend plots.