OpenAtlas

I suggest not to use information carrier as a subtype in the artifact type tree. The reason is, that any artifact can serve as information carrier. For example a tombstone would be defined as artifact and the main type would be tombstone no matter if it carries an inscription or not. The information contained in the inscription would be linked to the artifact via P128. Any human made object (formerly known as man made object E22) can carry information.
I guess we do not need to differentiate between information carrier and human made object anyway. If it carries information (P128) then it will be identified as "information object" because it has a link to a linguistic object (or a depiction etc.)

The merge of the type trees would only be needed to update projects with existing data (with links to different type trees). New projects will use only one type tree for artifact for the formerly distinguished find, artifact and information carrier from the beginning on and can than group inside it however they like.

But this raises another interesting question. As discussed artifacts and finds will share the same type tree but differ in their system_class because they function different, e.g. finds can only be added in combination of a strategraphic unit, are displayed differently on the map (in context with the strategraphic unit and other finds of the strategraphic unit), ...

So do we need to differentiate between artifact and information carrier in the user interface, e.g. has the user to choose at creation if it is an artifact or an information carrier because than different connections are available or are they used as one? In the later case they would of course share the same type tree and to deal with existing data I would take the whole information carrier type tree and put it as sub type into the artifacts tree.