The ability to update, delete and insert into the Named Item Collection items for excel named ranges.
Dave, thanks for your feedback! This is a very popular feature. We’ve started working on this and we’ll soon publish the design under the open-spec branch of the repository: https://github.com/OfficeDev/office-js-docs. Please stay tuned.
Office Extensibility Team
Maulik Kotadia commented
Very good suggestion Dave. I think read-only properties doesn't make sense.User should be able to do CRUD operations on NamedItemCollection