+Data structures
+---------------
+
+* `mmbuffer_t`, `mmfile_t`
+
+These store data usable for use by the xdiff backend, for writing and
+for reading, respectively. See `xdiff/xdiff.h` for the definitions
+and `diff.c` for examples.
+
+* `struct ll_merge_options`
+
+This describes the set of options the calling program wants to affect
+the operation of a low-level (single file) merge. Some options:
+
+`virtual_ancestor`::
+ Behave as though this were part of a merge between common
+ ancestors in a recursive merge.
+ If a helper program is specified by the
+ `[merge "<driver>"] recursive` configuration, it will
+ be used (see linkgit:gitattributes[5]).
+
+`variant`::
+ Resolve local conflicts automatically in favor
+ of one side or the other (as in 'git merge-file'
+ `--ours`/`--theirs`/`--union`). Can be `0`,
+ `XDL_MERGE_FAVOR_OURS`, `XDL_MERGE_FAVOR_THEIRS`, or
+ `XDL_MERGE_FAVOR_UNION`.
+
+`renormalize`::
+ Resmudge and clean the "base", "theirs" and "ours" files
+ before merging. Use this when the merge is likely to have
+ overlapped with a change in smudge/clean or end-of-line
+ normalization rules.
+