SDMN — No Notation for Item Definitions

Through the way that SDMN defines the relationships between Data Items, it provides the capability for graphically modeling Item Definitions. In some sense, the Data Item view is a subset of the full set of Item Definitions in the model.
Since there is a market need for Item Definition modeling as well as Data Item Library modeling, adding the Item Definition View makes sense.
SDMN already provides the capability of adding additional views, so this update would not change the basic structure of SDMN.