* `for_each_glob_ref_in()` the previous and `for_each_ref_in()` combined.
-* `head_ref_submodule()`, `for_each_ref_submodule()`,
- `for_each_ref_in_submodule()`, `for_each_tag_ref_submodule()`,
- `for_each_branch_ref_submodule()`, `for_each_remote_ref_submodule()`
- do the same as the functions described above but for a specified
- submodule.
+* Use `refs_` API for accessing submodules. The submodule ref store could
+ be obtained with `get_submodule_ref_store()`.
* `for_each_rawref()` can be used to learn about broken ref and symref.