When eZObjectRelationList (Object Relations) was introduced, it was supposed to gradually replace eZObjectRelation, reducing maintenance cost. We should deprecate eZObjectRelation to get this process moving.

From the commit log, svn rev 2675:

• Added new datatype eZObjectRelationList which will replace eZObjectRelation and also supports inline editing.

Things to do to ease the transition:

• Make a way to limit the amount of objects that can be related (integer)
• Make a conversion script for eZObjectRelation -> eZObjectRelationList
• Allow simple filters/sorts when there is only one relation