I think sort-mode accepts "value" (default) or "count" And
sort-direction, "forward" (default) and "reverse"
Then I continue to use the copy of the old documentation on web archive https://web.archive.org/web/20130526094042/http://simile.mit.edu/wiki/Exhibit/2.0/List_Facet
And I will change
data-ex-sort-direction, and so on.