enums, as they appear in the drop down for a user, are sorted in the enum settings themselves, regarding the database layer, it is a string, so sorting happens the same way as a string would be sorted.
keep in mind that you can keep an easy way to sort in the key of the enum, and keep it away from the users by editting the caption of each value.
adding to Leon's comment.
alongside the ENU, we also have a EnuSeqNr.
we can then pass the enu through the sub, and it returns an Int, that we can then map to the event, and sort.