Sort the repository contents in no particular ordering; this sorting is arbitrary, implementation-specific and subject to change at any time. This is the default sorting for new walkers.

Sort the repository contents in topological order (parents before children); this sorting mode can be combined with time sorting.

Sort the repository contents by commit time; this sorting mode can be combined with topological sorting.

Iterate through the repository contents in reverse order; this sorting mode can be combined with any of the above.