Unbiased 2mFo − DFc OMIT electron-density maps. (a, b) Overview of the electron density around Trp108 in unbiased 2mFo − DFc OMIT electron-density maps (contour level 1.2σ) calculated from the progressive micro (a) and progressive nano (b) data sets. (c, d) Unbiased 2mFo − DFc electron-density maps (contour level 1.2σ) calculated from the micro (c) and nano (d) data sets using as a starting model a truncated model of lysozyme lacking residues 96–116. Residues 96–116 are shown as pink sticks, while the residues used for generating the maps are shown as ribbon diagrams. That the electron-density maps shown in (c) and (d) cover virtually all of the atoms in residues 96–116 highlights the quality of the structural information contained in the progressive micro and progressive nano data sets.