+=item Interactive rebase
+
+With a laundered branch,
+one can do an interactive git rebase of the delta queue.
+
+=item New upstream rebase
+
+Start rebasing onto a new upstream version,
+turning C<...#..@-A-B-1-2-3> into C<(...#..@-A-B-, ...#'-)@'-1-2>.
+
+This has to be a wrapper around git-rebase,
+which prepares @' and then tries to rebase 1 2 onto @'.
+If the user asks for an interactive rebase,
+@' doesn't appear in the commit list, since
+@' is the newbase of the rebase (see git-rebase(1)).
+
+Note that the construction of @' cannot fail
+because @' simply copies debian/ from B and and everything else from #'.
+(Rebasing A and B is undesirable.
+We want the debian/ files to be non-rebasing
+so that git log shows the packaging history.)
+
+=item Stitch
+
+Make a pseudomerge,
+whose contributing parent to is the unstitched branch
+and
+whose overwritten parent is ffq-prev,
+consuming ffq-prev in the process
+(and writing debrebase-last instead).
+Ideally the contributing parent would be a laundered branch,
+or perhaps a laundered branch with a quilt patch addition commit.
+
+=item Commit quilt patches
+
+To generate a tree which can be represented as a
+3.0 (quilt) .dsc source packages,
+the delta queue must be reified inside the git tree
+in B<debian/patches/>.
+These patch files can be stripped out and/or regenerated as needed.
+
+=back
+
+=head1 COMMIT MESSAGE ANNOTATIONS
+
+git-debrebase makes annotations
+in the messages of commits it generates.
+
+The general form is
+
+ [git-debrebase[ COMMIT-TYPE [ ARGS...]]: PROSE, MORE PROSE]
+
+git-debrebase treats anything after the colon as a comment,
+paying no attention to PROSE.
+
+The full set of annotations is:
+ [git-debrebase: split mixed commit, debian part]
+ [git-debrebase: split mixed commit, upstream-part]
+ [git-debrebase: convert dgit import, debian changes]
+ [git-debrebase anchor: convert dgit import, upstream changes]
+
+ [git-debrebase upstream-combine . PIECE[ PIECE...]: new upstream]
+ [git-debrebase anchor: new upstream NEW-UPSTREAM-VERSION, merge]
+ [git-debrebase: new upstream NEW-UPSTREAM-VERSION, changelog]
+ [git-debrebase: export and commit patches]
+
+ [git-debrebase convert-from-gbp: drop patches]
+ [git-debrebase anchor: declare upstream]
+ [git-debrebase pseudomerge: stitch]
+
+ [git-debrebase convert-to-gbp: commit patches]
+
+Only anchor merges have the C<[git-debrebase anchor: ...]> tag.
+Single-parent anchors are not generated by git-debrebase,
+and when made manually should not
+contain any C<[git-debrebase ...]> annotation.
+
+The C<split mixed commit> and C<convert dgit import>
+tags are added to the pre-existing commit message,
+when git-debrebase rewrites the commit.
+
+=head1 APPENDIX - DGIT IMPORT HANDLING
+
+The dgit .dsc import format is not documented or specified
+(so some of the following terms are not defined anywhere).
+The dgit import format it is defined by the implementation in dgit,
+of which git-debrebase has special knowledge.
+
+Consider a non-dgit NMU followed by a dgit NMU:
+
+ interchange --/--B3!--%--//----D*-->
+ / /
+ % 4
+ / 3
+ / 2
+ / 1
+ 2 &_
+ / /| \
+ 1 0 00 =XBC%
+ /
+ /
+ --@--A breakwater
+ /
+ --#--------> upstream
+
+
+ Supplementary key:
+
+ =XBC% dgit tarball import of .debian.tar.gz containing
+ Debian packaging including changes B C and quilt patches
+ 0 dgit tarball import of upstream tarball
+ 00 dgit tarball import of supplementary upstream piece
+ &_ dgit import nearly-breakwater-anchor
+ // dgit fetch / import-dsc pseudomerge to make fast forward
+
+ &' git-debrebase converted import (upstream files only)
+ C' git-debrebase converted packaging change import
+
+ * ** before and after HEAD
+
+We want to transform this into:
+
+=over
+
+=item I. No new upstream version
+
+ (0 + 00 eq #)
+ --/--B3!--%--//-----D*-------------/-->
+ / / /
+ % 4 4**
+ / 3 3
+ / 2 2
+ / 1 1
+ 2 &_ /
+ / /| \ /
+ 1 0 00 =XBC% /
+ / /
+ / /
+ --@--A-----B---------------------C'---D
+ /
+ --#----------------------------------------->
+
+=item II. New upstream
+
+ (0 + 00 neq #)
+
+ --/--B3!--%--//-----D*-------------/-->
+ / / /
+ % 4 4**
+ / 3 3
+ / 2 2
+ / 1 1
+ 2 &_ /
+ / /| \ /
+ 1 0 00 =XBC% /
+ / /
+ / /
+ --@--A-----B-----------------@---C'---D
+ / /
+ --#--------------------- - - / - - --------->
+ /
+ &'
+ /|
+ 0 00