Many of the sort commands ignore case differences when comparing, if
@code{sort-fold-case} is non-@code{nil}.
-@node Narrowing, Two-Column, Sorting, Top
+@node Narrowing, Diff Mode, Sorting, Top
@section Narrowing
@cindex widening
@cindex restriction
if you enable the command, confirmation will no longer be required for
it. @xref{Disabling}.
-@node Two-Column, Editing Binary Files, Narrowing, Top
+@node Diff Mode, Two-Column, Narrowing, Top
+@section Diff Mode
+@cindex Diff mode
+
+ Diff mode is useful for editing patches and comparisons produced by
+the @command{diff} program. You can select Diff mode by typing
+@kbd{M-x diff-mode}; Emacs commands that compare files automatically
+select Diff mode. @xref{Top,, Diff, diff, Comparing and Merging Files},
+for more information about @command{diff} output formats.
+
+ One general feature of Diff mode is that manual edits to the patch
+automatically correct line numbers, including those in the hunk
+header, so that you can actually apply the edited patch. Diff mode
+also provides the following commands to navigate, manipulate and apply
+parts of patches:
+
+@table @kbd
+@item M-n
+Move to the next hunk-start (@code{diff-hunk-next}).
+
+@item M-p
+Move to the previous hunk-start (@code{diff-hunk-prev}).
+
+@item M-@}
+Move to the next file-start, in a multi-file patch
+(@code{diff-file-next}).
+
+@item M-@{
+Move to the previous file-start, in a multi-file patch
+(@code{diff-file-prev}).
+
+@item M-k
+Kill the hunk at point (@code{diff-hunk-kill}).
+
+@item M-K
+In a multi-file patch, kill the current file part.
+(@code{diff-file-kill}).
+
+@item C-c C-a
+Apply this hunk to its target file (@code{diff-apply-hunk}). With a
+prefix argument of @kbd{C-u}, revert this hunk.
+
+@item C-c C-c
+Go to the source corresponding to this hunk (@code{diff-goto-source}).
+
+@item C-c C-e
+Start an Ediff session with the patch (@code{diff-ediff-patch}).
+@xref{Top, Ediff, Ediff, ediff, The Ediff Manual}.
+
+@item C-c C-n
+Restrict the view to the current hunk (@code{diff-restrict-view}).
+@xref{Narrowing}. With a prefix argument of @kbd{C-u}, restrict the
+view to the current patch of a multiple file patch. To widen again,
+use @kbd{C-x n w}.
+
+@item C-c C-r
+Reverse the direction of comparison for the entire buffer
+(@code{diff-reverse-direction}).
+
+@item C-c C-s
+Split the hunk at point (@code{diff-split-hunk}). This is for
+manually editing patches, and only works with the unified diff format.
+
+@item C-c C-u
+Convert the entire buffer to unified format
+(@code{diff-context->unified}). With a prefix argument, convert
+unified format to context format. In Transient Mark mode, when the
+mark is active, this command operates only on the region.
+
+@item C-c C-w
+Refine the current hunk so that it disregards changes in whitespace
+(@code{diff-refine-hunk}).
+@end table
+
+ @kbd{C-x 4 a} in Diff mode operates on behalf of the target file,
+but gets the function name from the patch itself. @xref{Change Log}.
+This is useful for making log entries for functions that are deleted
+by the patch.
+
+@node Two-Column, Editing Binary Files, Diff Mode, Top
@section Two-Column Editing
@cindex two-column editing
@cindex splitting columns