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c.shoemaker@cox.net  committed 59df2a1

Minor clarifications in diffcore documentation

Signed-off-by: Chris Shoemaker <c.shoemaker at cox.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

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File Documentation/diffcore.txt

 Introduction
 ------------
 
-The diff commands git-diff-index, git-diff-files, and
-git-diff-tree can be told to manipulate differences they find
-in unconventional ways before showing diff(1) output.  The
-manipulation is collectively called "diffcore transformation".
-This short note describes what they are and how to use them to
-produce diff outputs that are easier to understand than the
-conventional kind.
+The diff commands git-diff-index, git-diff-files, git-diff-tree, and
+git-diff-stages can be told to manipulate differences they find in
+unconventional ways before showing diff(1) output.  The manipulation
+is collectively called "diffcore transformation".  This short note
+describes what they are and how to use them to produce diff outputs
+that are easier to understand than the conventional kind.
 
 
 The chain of operation
  - git-diff-files compares contents of the index file and the
    working directory;
 
- - git-diff-tree compares contents of two "tree" objects.
+ - git-diff-tree compares contents of two "tree" objects;
+
+ - git-diff-stages compares contents of blobs at two stages in an
+   unmerged index file.
 
 In all of these cases, the commands themselves compare
 corresponding paths in the two sets of files.  The result of
 diff-patch format.
 
 
-diffcore-pathspec
+diffcore-pathspec: For Ignoring Files Outside Our Consideration
 -----------------
 
 The first transformation in the chain is diffcore-pathspec, and
 is controlled by giving the pathname parameters to the
 git-diff-* commands on the command line.  The pathspec is used
 to limit the world diff operates in.  It removes the filepairs
-outside the specified set of pathnames.
+outside the specified set of pathnames.  E.g. If the input set 
+of filepairs included:
+
+------------------------------------------------
+:100644 100644 bcd1234... 0123456... M junkfile
+------------------------------------------------
+
+but the command invocation was "git-diff-files myfile", then the
+junkfile entry would be removed from the list because only "myfile"
+is under consideration.
 
 Implementation note.  For performance reasons, git-diff-tree
 uses the pathname parameters on the command line to cull set of
 use diffcore-pathspec, but the end result is the same.
 
 
-diffcore-break
+diffcore-break: For Splitting Up "Complete Rewrites"
 --------------
 
 The second transformation in the chain is diffcore-break, and is
 after "-B" option (e.g. "-B75" to tell it to use 75%).
 
 
-diffcore-rename
+diffcore-rename: For Detection Renames and Copies
 ---------------
 
 This transformation is used to detect renames and copies, and is
 :100644 100644 0123456... 0123456... R100 fileX file0
 ------------------------------------------------
 
-When the "-C" option is used, the original contents of modified
-files and contents of unchanged files are considered as
-candidates of the source files in rename/copy operation, in
-addition to the deleted files.  If the input were like these
-filepairs, that talk about a modified file fileY and a newly
+When the "-C" option is used, the original contents of modified files,
+and deleted files (and also unmodified files, if the
+"\--find-copies-harder" option is used) are considered as candidates
+of the source files in rename/copy operation.  If the input were like
+these filepairs, that talk about a modified file fileY and a newly
 created file file0:
 
 ------------------------------------------------
 :100644 100644 0123456... 1234567... M fileY
-:000000 100644 0000000... 0123456... A file0
+:000000 100644 0000000... bcd3456... A file0
 ------------------------------------------------
 
 the original contents of fileY and the resulting contents of
 
 ------------------------------------------------
 :100644 100644 0123456... 1234567... M fileY
-:100644 100644 0123456... 0123456... C100 fileY file0
+:100644 100644 0123456... bcd3456... C100 fileY file0
 ------------------------------------------------
 
 In both rename and copy detection, the same "extent of changes"
 algorithm used in diffcore-break is used to determine if two
 files are "similar enough", and can be customized to use
-similarity score different from the default 50% by giving a
-number after "-M" or "-C" option (e.g. "-M8" to tell it to use
+a similarity score different from the default of 50% by giving a
+number after the "-M" or "-C" option (e.g. "-M8" to tell it to use
 8/10 = 80%).
 
 Note.  When the "-C" option is used with `\--find-copies-harder`
 copied happened to have been modified in the same changeset.
 
 
-diffcore-merge-broken
+diffcore-merge-broken: For Putting "Complete Rewrites" Back Together
 ---------------------
 
 This transformation is used to merge filepairs broken by
 version prefixed with '+'.
 
 
-diffcore-pickaxe
+diffcore-pickaxe: For Detecting Addition/Deletion of Specified String
 ----------------
 
 This transformation is used to find filepairs that represent
 opposite case that loses the specified string.
 
 When `\--pickaxe-all` is not in effect, diffcore-pickaxe leaves
-only such filepairs that touches the specified string in its
+only such filepairs that touch the specified string in its
 output.  When `\--pickaxe-all` is used, diffcore-pickaxe leaves all
 filepairs intact if there is such a filepair, or makes the
 output empty otherwise.  The latter behaviour is designed to
 changeset easier.
 
 
-diffcore-order
+diffcore-order: For Sorting the Output Based on Filenames
 --------------
 
 This is used to reorder the filepairs according to the user's
 (or project's) taste, and is controlled by the -O option to the
 git-diff-* commands.
 
-This takes a text file each of whose line is a shell glob
+This takes a text file each of whose lines is a shell glob
 pattern.  Filepairs that match a glob pattern on an earlier line
 in the file are output before ones that match a later line, and
 filepairs that do not match any glob pattern are output last.
 
-As an example, typical orderfile for the core git probably
+As an example, a typical orderfile for the core git probably
 would look like this:
 
 ------------------------------------------------