The FileTool can be used to generate a Cell Hierarchy Digest (CHD) file. The file format is the same as produced with the Save button in the Cell Hierarchy Digests panel. The CHD file can subsequently be read into the Cell Hierarchy Digests panel with the Add button.
The command line takes the form:
filetool [-set variables] -cfile -i layout_file -o chd_file [-g] [-c]
If the -g option is given, geometry records will be included in the file. These records are effectively a concatenation of a Cell Geometry Digest file representation. Layer filtering can be employed to specify layers to include.
The resulting file is a highly compact but easily random-accessible representation of the layout file.
Future releases of Xic will make use of these files in creative ways, stay tuned.
The -c option will skip use of compression when creating the file. Files produced with this option (and without geometry) should be compatible with Xic release 3.2.16 and earlier, which did not support compression. If backward compatibility is not needed, this option should not be used.