Howard Chu writes:
This is the first stage in a larger transition, to using sorted arrays for multivalued attributes. I haven't quite decided how the next steps will play out just yet. (...) We can also implement this without any user-visible change, if we keep an auxiliary ordering array, the way the current sorter does. But it seems to me that that will be too much memory overhead. It also makes add/remove that much more tedious...
Add a slapd.conf directive which inserts an implicit X-ORDERED 'VALUES' in an already existing attribute definition. Then admins can configure the old behavior for the attributes where he needs it, including in preexisting schema. (Could support @objectclass and !objectclass to list multiple attributes, or a regex matching the attribute name.)