**   --dark                      Use dark mode for the Tcl/Tk-based GUI and HTML
**   --diff-binary BOOL          Include binary files with external commands
**   --exec-abs-paths            Force absolute path names on external commands
**   --exec-rel-paths            Force relative path names on external commands
**   -r|--from VERSION           Select VERSION as source for the diff
**   -w|--ignore-all-space       Ignore white space when comparing lines
**   -i|--internal               Use internal diff logic
**   --invert                    Invert the diff
**   --json                      Output formatted as JSON
**   -n|--linenum                Show line numbers
**   -N|--new-file               Alias for --verbose
**   --numstat                   Show only the number of added and deleted lines
**   -y|--side-by-side           Side-by-side diff
**   --strip-trailing-cr         Strip trailing CR
**   --tcl                       Tcl-formated output used internally by --tk
**   --tclsh PATH                Tcl/Tk shell used for --tk (default: "tclsh")
**   --tk                        Launch a Tcl/Tk GUI for display