I think creation_date is a default/universal sorting, unless activity_date is available. _{^{(But you know what they say happens when you "ASSUME".)‡}}

Evidence for:

• Seems like it would be required if paging is going to work well.
• This post has 753 edits (759 revision entries) and the creation dates are all in descending order.
• This post has 429 edits (502 revision entries) and it has at least 1 edit of each subtype ([title, body, tag] x [edit, rollback] + suggested edit). The creation dates are all in descending order.
• Other routes seem to sort by creation_date although sorting parameters are not supported by the route.
• Likewise, /events sorts by creation_date, descending, despite that being unmentioned in the livedoc.
• This way old answer about API version 1, has the lead developer saying:

Because sorting by dates is much more common than by name, ordering is descending by default.

• The various inconsistent behaviors as documented in the unresolved bugs here on Stack Apps. And on Meta Stack Exchange, and on Meta Stack Overflow.

^{‡ They say that you've made a cost-effective branching decision based on knowledge and experience. And that it in no way precludes you observing-for and reacting-to signs that the assumption was false.}

I think creation_date is a default/universal sorting, unless activity_date is available. _{^{(But you know what they say happens when you "ASSUME".)‡}}

Evidence for:

• Seems like it would be required if paging is going to work well.
• This post has 753 edits (759 revision entries) and the creation dates are all in descending order.
• This post has 429 edits (502 revision entries) and it has at least 1 edit of each subtype ([title, body, tag] x [edit, rollback] + suggested edit). The creation dates are all in descending order.
• Other routes seem to sort by creation_date although sorting parameters are not supported by the route.
• Likewise, /events sorts by creation_date, descending, despite that being unmentioned in the livedoc.
• This way old answer about API version 1, has the lead developer saying:

Because sorting by dates is much more common than by name, ordering is descending by default.

• It's not explicitly stated anywhere.
• The various inconsistent behaviors as documented in the unresolved bugs here on Stack Apps. And on Meta Stack Exchange, and on Meta Stack Overflow.

^{‡ They say that you've made a cost-effective branching decision based on knowledge and experience. And that it in no way precludes you observing-for and reacting-to signs that the assumption was false.}